Glossary

Alphabetical Listing

A

A-Pillar: The frontmost roof support of a vehicle, located in most cases between the outer edge of the windshield and the leading edge of the front door window frame.
Accelerator: The foot pedal that makes the car go faster. Also called the "gas pedal".
Active Fuel Management: Active Fuel Management^® is GM's fuel-saving technology that enables engines to automatically and seamlessly operate on reduced cylinders when full power is not needed. When load demands increase, such as when the vehicle accelerates or travels uphill, cylinders are reactivated to provide full power. The result is an improvement in fuel efficiency .
Air Bags: Protect passengers involved in collisions by providing a cushion to prevent additional impact with vehicle parts such as the steering wheel or dashboard. Manufacturers offer them in different configurations, which may include any or all of driver's side, dual front and/or side panel, and roof rail head curtain.; All new General Motors vehicles feature air bags, which deploy with reduced force. Note, though, that air bags are intended to supplement vehicles' safety belts, not replace them. As well, children (with or without car seats) and small adults should never be seated in the front seat of a car equipped with a passenger-side air bag.; Many GM products feature Head Curtain Air Bags that drop like inflated curtains on both sides of the front and/or rear passenger compartment to help protect against head and/or neck injuries in a side-impact collision.
All-Wheel Drive: See Drive.
Alloy Wheel: A generic term used to describe any road wheel not manufactured from steel. (An "alloy" is a mixture of two or more metals.) The most common alloy wheels are made from cast-aluminum.
All-Season Tire: A steel-belted radial tire which has been designed to provide balanced performance on wet and dry roads and traction in mud and snow. *
Alternator: A device which converts mechanical energy from the engine into electric energy. The alternator is used to charge the battery and operate the vehicle's electrical components.
Annual Percentage Rate (APR): The interest rate used in the calculation of a monthly lease or finance payment.
Anti-lock Braking System (ABS): A braking system which modulates brake pressure to allow maximum braking without wheel lock-up. ABS can help drivers maintain steering control during hard braking, even on slick surfaces and under varying load conditions.
Aspect Ratio: Part of the system of how a tire size is designated for a vehicle; determined by dividing the height of a tire's sidewall by the width of its tread.
Audible Front Disc Brake Wear Sensors: These sensors alert the driver when brake pads should be replaced by emitting a high-pitched squeal.
Automatic Day/Night Mirror: A rearview mirror made with two layers of glass separated by a light-sensitive chemical. The chemical automatically darkens to absorb glare from the headlamps of a following vehicle. Also known as an electrochromic auto-dimming mirror.
Automatic Light Control: A system (found on many GM vehicles) which automatically brings the headlights up to full intensity — or turns them and other exterior lights on if they are not part of the Daytime Running Lamp function — in response to external lighting conditions. It also turns the lights off when the vehicle is not in use, helping avoid a dead battery due to driver oversight.
Automatic Power Door Locks with Programmable Feature: A safety feature which automatically locks all doors when the transmission is put into gear. Depending on the vehicle, this feature offers different programming options to suit drivers' preferences.

B

B-Pillar: The roof support between a vehicle's front door window and rear side window, if there is one.
Base-Coat/Clear-Coat: A paint system which adds a final clear-coat paint layer on top of the colour coats to provide a deep, long-lasting "wet-look" shine.
Battery: The device which provides electrical power for engine starting and for electrical accessories when the engine is off.
Battery Run-Down Protection: A system that automatically shuts off all interior lights after 20 minutes. The system also shuts off power to the clock/radio and the remote locking system if the vehicle is left untouched for more than 20 days.
Block Heater: A device which uses electric power to warm the engine block and oil in very cold conditions, allowing easier starting and faster warmups.
Brake Pad: On a disc brake, a pad of high-friction material that is pressed against the turning disc to slow the wheel to which the disc is attached.
Brake Shoe: In a drum brake, a semi-circular piece of high-friction material that presses against the inside of the turning brake drum to slow the wheel to which the drum is attached.
Brake/Transmission Shift Interlock: A safety system which prevents the driver from moving an automatic transmission out of "Park" unless the brake pedal is depressed.
Breakaway Switch: A safety device which automatically applies a trailer's brakes if it should accidentally become separated from its tow vehicle.
Bumper Hitch: A bumper mounting location for a trailer hitch ball.

C

C-Pillar: On a vehicle with two windows per side, the roof support between the vehicle's rearmost side window and its rear window. (On vehicles such as wagons and vans which have a third side window, the rearmost roof support is called the D-Pillar.)
Cabin Filter: A filter which improves the interior air quality of a vehicle by reducing the amount of small air-borne particles. Also known as a pollen filter.
Caliper: In a disc braking system, the portion of the brake that carries the brake pads and "pinches" the disc to create friction and slow the vehicle.
Cap Cost Reduction: A down payment to reduce the vehicle price or "cap cost" (capital cost) of the vehicle. It can take the form of either a cash down payment or a vehicle trade-in and is applied to the lease at the time of lease signing. A cap cost reduction helps to reduce your monthly payment.
Capitalized Cost: Commonly referred to as the "Cap Cost", this is the lease price plus any administrative fee and other items included in the lease such as extended service contracts, life, accident and health insurance policies.
Catalytic Converter: Part of a vehicle's exhaust system, this stainless steel canister contains materials that cause chemical reactions which convert exhaust emissions into less harmful components before they enter the atmosphere.
Centre High-Mounted Stop Lamp (CHMSL): A red lamp located high on the rear of the vehicle to warn following drivers whenever the brakes are applied, helping to avoid accidents.
CFC-Free Air Conditioning: A non-ozone-depleting air conditioning technology.
Child-Security Rear Door Locks: A system which, when activated, prevents rear seat passengers from using their inside door handles to open the rear doors.
Child Shoulder Belt Comfort Guides: Rear shoulder belt anchors which adjust to hold shoulder belts in a more comfortable and secure position for smaller passengers.
Climate Control: An automatic heating, ventilation and air conditioning (HVAC) system which gives passengers control over the temperature in their vehicle.
Closed-End Lease: A lease arrangement under which you, as the lessee, will have no responsibility to the lessor for the market value of the vehicle at scheduled lease termination, if the vehicle does not have excess kilometrage or wear. This type of lease is sometimes called a "walk-away lease".
Clutch: A mechanical device which engages and disengages a vehicle's engine from its transmission, allowing the transmission's gears to be shifted.
Coupe: Term usually used to describe any car with a fixed roof and two doors.
Cruise Control: An electronically controlled device which automatically maintains a set speed without the need for constant driver input.
Crush Zones: A body structure designed to crush at a progressively controlled rate, in order to dissipate the forces from a collision before the impact reaches the passenger compartment.
Curb Weight: The vehicle weight without the driver, passengers and cargo. This weight includes the maximum fuel, fluids and other items of standard equipment.
Cylinder: The round, straight-sided cavity inside the engine block in which the pistons move up and down.
Cylinder Head: Located directly above the cylinders, this is the aluminum or iron housing that contains the combustion chambers, intake and exhaust ports and much or all of the valve train.

D

Dashboard: Otherwise known as the dash, this is the full-width front panel which usually includes the instruments, accessory controls and glove box.
Daytime Running Lamps: A system that makes the vehicle more visible to other drivers and pedestrians by partially illuminating front lights during the day.
Detonation: Detonation in gasoline engines is usually caused by heat or pressure resulting in an explosion of the unburnt portion of the fuel (knocking). This force is extremely destructive to engines, and may result in holes blown through the top of pistons or engine blocks. Diesel engines actually use detonation as their primary method of extracting energy from diesel.
Diesel: A type of engine which runs on diesel fuel rather than gasoline. These engines don't use spark plugs in their ignition systems. Instead, ignition of the air/fuel mixture comes from heat generated by high compression in the combustion chamber.
Differential: This part distributes power from the engine to the wheels. For example, differentials within the axles of rear-wheel drives are designed to split torque evenly.
Direct Ignition System (DIS): A computer-controlled ignition system. Sensor-driven, DIS replaces the conventional distributor, which uses a cam gear to time engine sparking.
Disc Brakes: Properly called caliper disc brakes, the design features a caliper which straddles a disc-shaped rotor which turns with the wheel. When you apply the brakes, the calipers slowly squeeze the rotor between two pads, slowing the rotor — and wheel — through friction. Experts tend to recommend disc brakes over drum brakes due to their efficiency at high temperatures and in wet weather.
Displacement: The measurement of the actual volume swept out by the piston as it travels from the bottom to the top of the cylinder, multiplied by the total number of cylinders in the engine. Usually expressed in litres (L) or cubic inches (cu. in.).
Double Overhead Camshafts (DOHC): Also known as dual overhead camshafts or "twin cams". Unlike a conventional engine which has one camshaft in each cylinder head, a DOHC engine features two camshafts per cylinder head: one controls the intake valves while the other controls the exhaust valves. This configuration helps the engine build speed more quickly and breathe more easily.
Drag Coefficient: A measure of the aerodynamic sleekness of an object. The lower the number, the greater the aerodynamic efficiency and the "slipperier" the object. For a vehicle, this translates into reduced wind resistance, which could provide better handling and stability, and in general, greater fuel efficiency, and less noise in the passenger compartment.
"Drive": Signifies how the engine's power is transferred to the driving wheels:; Front-Wheel Drive (FWD) — Most common among sedans and coupes as it allows for more passenger and cargo room and delivers excellent traction;; Rear-Wheel Drive — Usually found in most sports cars and trucks as it generally offers the best handling, towing and cargo-hauling abilities;; All-Wheel Drive (AWD)— transfers power to all four wheels all the time and can vary the split front to rear, and in some applications, side-to-side;; Four-Wheel Drive ("4x4") — Transfers power to all four wheels only on driver demand. When not engaged, systems usually supply power to rear wheels only.
Driveshaft: A shaft in rear-wheel drive vehicles which transmits power from the transmission in the front to the differential at the rear.
Drum Brakes: A common type of braking system which forces two brake shoes against the inside of a brake drum which turns with the wheel. Considered less efficient system than disc brakes.
Dual Braking System: A safety feature which splits the four brakes into two separate hydraulic circuits, thereby avoiding complete brake loss should one set fail. This system is complemented by a warning light which alerts the driver in the event that either half fails.

E

E85: E85 is an alcohol fuel mixture that typically contains a mixture of up to 85% denatured fuel ethanol and gasoline or other hydrocarbon by volume. While corn is the primary source material for ethanol fuel production in North America, new methods are currently being developed.
Electric Vehicle: An electric car is one that uses chemical energy stored in rechargeable battery packs, and electric motors and motor controllers instead of an internal combustion engine. GM's Chevrolet Volt is a good example of an Extended Range Electric Vehicle (E-REV).
Electronic Fuel Injection (EFI): An electronic system which measures an engine's fuel needs and regulates the flow of fuel while automatically adjusting the fuel/air mixture for optimal engine performance. This system has replaced carburetors in virtually all modern engines.
Emissions Control: Any device on an engine specifically designed to reduce, remove or control harmful engine emissions. (See "Catalytic Convertor".)
Energy-Absorbing Steering Column: A feature which allows the steering column to compress on impact.
Enhanced Traction System: A form of traction control system which helps to prevent wheelspin by managing the amount of engine torque applied to the driving wheels. Unlike traction control systems, an Enhanced Traction System does not apply the vehicle's brakes.
Excess Kilometrage: Any kilometrage exceeding the allowed kilometrage as outlined in a lease agreement. Most lease agreements allow you to drive 24,000 kilometres per year. If you think you are going to drive more than the standard 24,000 kilometres per year average, you can arrange to include the cost of additional kilometrage in your monthly payment, at a reduced excess "per-kilometre" rate.
Excess Kilometrage Charge: A charge per kilometre that is assessed for kilometrage driven in excess of what is stipulated in a lease agreement.
Excess Wear and Tear: Excess wear and tear is evaluated at lease end. Broken or missing parts on the inside and out, poor quality repairs, mechanical and electrical damage, and alterations to the car's appearance all constitute excess wear and tear. Be sure to talk about this with your dealer when you lease. Please know that normal wear and tear is okay. It includes such minor items as small door dings and scratches that don't penetrate the paint finish.
Exhaust Manifold: The network of passages designed to collect exhaust gases from each exhaust port and route them toward the catalytic converter, muffler and the exhaust system.
Express-Open Power Sunroof: A power-operated sunroof which opens completely or at pre-determined intervals with a single touch of the control button.

F

Fade: Less effective braking caused by overheated brakes. Brake fade usually occurs after long and overly aggressive braking. Disc brakes are less prone to fade than drum brakes, and many vehicles feature special ventilated disc brakes, which further reduce the likelihood of brake fade.
Final-Drive Ratio: The reduction ratio of the gearset located in the drivetrain that is furthest from the engine, typically the rear axle or transaxle ratio.
Flash-to-Pass: A convenience feature which allows the driver to activate the high-beam headlights, signaling vehicles ahead that the driver is intending to pass.
Flush-Mounted Glass: A design system in which window glass is installed almost flush with the body surface, reducing aerodynamic drag and wind noise.
Fog Lights: Lights designed to supplement a vehicle's headlights in fog and other low-visibility conditions—they work by lighting up the lower area directly in front of the vehicle.
Four-Wheel Steering: A steering system which controls all four wheels simultaneously.
Four-Wheel Drive: See Drive.
Fuel Cell: A fuel cell is a device that converts chemical energy from hydrogen and oxygen into electrical energy and produces an electrical current. It is similar to a battery, but it generates energy rather than simply storing it. A fuel cell is also similar to an internal combustion engine, except that it operates at low temperatures with minimal moving parts and produces water as opposed to exhaust.
Fuel Efficiency: Fuel efficiency more commonly refers to the energy efficiency of a particular vehicle model, where its total output (range or kilometres) is given as a ratio of range units per a unit amount of input fuel (gasoline, diesel, etc.). This is usually represented as km/L. Also see Active Fuel Management^®.
Fuel Injection: See Electronic Fuel Injection.

G

GCWR: An acronym for a vehicle's Gross Combined Weight Rating. The GCWR is the maximum weight a vehicle should reach in use, including the vehicle itself, passengers, cargo, trailer, etc. The GCWR is set by the manufacturer, and exceeding it is unsafe.
GVWR: An acronym for a vehicle's Gross Vehicle Weight Rating. The GVWR is the maximum weight a vehicle should reach in use, including the vehicle itself, passengers and cargo, but not including a trailer. The GVWR is set by the manufacturer, and exceeding it is unsafe.
Galvanized Steel: A special zinc-coated steel used in many painted and key unpainted areas of a vehicle to prevent rust and corrosion. GM uses two-sided galvanized steel extensively on many vehicles to enhance corrosion resistance.
Gear Ratio: The number of revolutions a driving gear needs in order to turn a driven gear through one complete revolution.
Grid Antenna: A radio antenna embedded into a vehicle's front or rear window, making it almost invisible and protecting it from vandalism or damage.
Gross Axle Weight (GAW): The actual weight that a particular axle is carrying.
Gross Axle Weight Rating (GAWR): The load-carrying capacity of a vehicle, specified by the vehicle manufacturer, as measured at the tire-ground interfaces.
Guaranteed Option to Purchase Price: This is the amount you can pay to purchase your vehicle at the end of your lease. This amount is established up-front when you sign your lease agreement.

H

Halogen: A group of elements used in their gaseous state in the bulbs of a variety of modern automotive headlamps. Halogen headlamps cast a more brilliant beam than conventional lights.
Handling: A general term used to describe how a vehicle feels, reacts and behaves on the road.
HID Headlights: High-Intensity Discharge (HID) lighting provides about twice the brightness of ordinary headlights. HID lamps use electrodes and a gas, usually xenon, to create light. They use less power than conventional headlights and can last up to 160,000 km (100,000 miles) of driving time.
Univeral Home Remote: Univeral Home Remote wireless control system is an integrated transceiver (a transmitter and receiver) that can be programmed to activate radio frequency (RF) devices such as garage doors, estate/community gates, entry door locks, home/office lighting, or other RF devices. It is available on many GM vehicles.
Horsepower: A standard measurement used to record the amount of work that can be done in a certain amount of time. The horsepower of an engine depends on the engine's torque and speed: In passenger cars and trucks it is usually calculated in Net terms; at the flywheel with all of the engine accessories and exhaust system installed and operating. (See Performance for more.)
Hybrid: Hybrid refers to a vehicle that is powered by more than one type of energy, usually gasoline and electric. Many vehicle manufacturers currently have vehicles on the road that use both gasoline engines and electric engines, combining tried-and-true gas engine effectiveness with the environmental and fuel saving advantages of electric.
Hydraulic: Systems which use a fluid moving through a channel to accomplish their goals. In vehicles, hydraulics are often used in the braking and handling systems. Some vehicles even use hydraulics to absorb engine vibrations which might otherwise be felt in the passenger compartment.
Hyrdogen Fuel Cell: A fuel cell is like a battery. It works by harnessing the electricity created in the chemical reaction that occurs when hydrogen from a vehicle's fuel tank and oxygen from the air combine. This electricity is stored within the fuel cell, and hundreds of these fuel cells (or stacks) can be used to power vehicles. Since the conversion of the fuel to energy takes place via an electrochemical process, not combustion, a hydrogen fuel cell vehicle is a zero-emissions vehicle that only emits water and heat as its waste products. The overall process is clean, quiet and highly efficient - two to three times more efficient than internal combustion.

I

Independent Suspension: Any suspension which prevents the movement of one wheel from directly affecting the movement of the opposite wheel. This ensures a smoother, more comfortable ride. May come in one of two forms: independent front suspension only; or fully independent — in which all four wheels can move up and down individually, each one not affecting the other in movement.
Instrumentation: The displays on the instrument panel which tell the driver about the mechanical and electrical operation of the vehicle.

J

K

Knock: "Knock" or "knocking" is a pounding noise made by an engine, often as a result of poor fuel combustion. It is also called ping. If your vehicle suffers audible engine knock at highway speeds, higher octane fuels might be necessary.

L

L-Type Engine: An engine layout characterized by an "inline" single bank of cylinders. For instance, the designation L4 indicates a 4-cylinder engine with an "inline" cylinder layout. (See "V-Type engine" for comparison.)
Lease: An agreement under which the vehicle owner (the lessor) permits its use by a customer (the lessee) for an agreed upon period of time (the term).
Lease Term: The length of time of a lease agreement.
Lessee: You, the user of the leased vehicle.
Lift: The tendency of a vehicle's front end to rise up during acceleration. The term "lift" is also used when describing the lifting pressure exerted by air flowing under the vehicle at higher speeds. While Lift can reduce traction and stability, new aerodynamic underbody designs and the use of features like front air dams and rear spoilers can reduce or eliminate the condition.
Limited-Slip Differential: A differential in a rear-drive vehicle which can limit speed and torque differences in both driving wheels. Limited slip ensures that both wheels will have a certain degree of torque, even if one is on a very slippery surface.
Live Axle: Also called a "driving axle," a live axle features a differential and axle shafts to power the two driving wheels it's connected to.
Locking Rear Differential: A differential in a rear-drive vehicle designed to force torque to the driving wheel with the most traction when one wheel slips. Ideal for driving in poor traction conditions such as mud and snow.

M

MSRP: The "Manufacturer's Suggested Retail Price". This is a value determined by the manufacturer as a reasonable price to pay for the vehicle.
MacPherson Strut: An independent suspension system consisting of a two-in-one combination shock absorber/coil spring mechanism at each wheel.
Mag: Short for magnesium, a metal sometimes used for the wheels of race cars because of its light weight.
Metallic Paint: A type of paint containing very fine metallic particles which make the paint appear to sparkle.
Model/Body Weight: A vehicle's basic model weight is the total of curb weight plus occupants (measured by multiplying the standard seating capacity by 68 kg /150 lb.). However, the total model weight usually varies with each vehicle, depending on such modifications as options and substitutions.
Mouldings: Durable composite strips attached horizontally to the side of a vehicle's body. Bodyside mouldings serve to enhance appearance while offering protection from minor dents and scratches.
Multi-link Suspension: Any independent suspension having 3 control arms or more is considered multi-link. Multi-link suspension offers superior handling and requires less space than some types of suspensions, but can also be more expensive. Multi-link suspension is typically found on mid-size sedans, luxury vehicles and sports cars.
Multi-Port Fuel Injection (MFI): A system which uses individual fuel injectors to spray fuel directly into each intake port. Avoiding the intake manifold makes fuel delivery much more efficient.

N

O

Octane: Gas with higher octane levels enables the air/fuel mixture to withstand higher compression levels without resulting in engine knocking noises, or "knock". Higher octane gas is often required with high-performance engines.
Odometer: A display instrument which measures and records the total distance ever travelled by the vehicle. A trip odometer often supplements the mileage odometer: Drivers can use it to measure a specific distance travelled and then reset it to zero.
Onboard Diagnostics (OBD): A built-in electronic system designed to identify and help analyze problems which may affect certain vehicle systems. All GM vehicles feature advanced onboard diagnostic systems.
OnStar: OnStar^® is a factory-installed communication system that uses Global Positioning System (GPS) satellite and cellular technology to link the vehicle and driver to the OnStar Centre. Live, specially trained Advisors offer real-time, personalized help 24 hours a day, 365 days a year.* OnStar is standard on many new GM cars and trucks sold in Canada and the United States.; * Visit OnStar^® for coverage map, details and system limitations. Services vary by model and conditions.
Open-End Lease: A lease in which you are held responsible for the vehicle's residual value at lease termination. If the actual value turns out to be less than the residual value, you may be held responsible for all or a portion of the difference; if more, then you may be entitled to a share of sale proceeds.
Overdrive: Any gearset which enables the driving wheels to turn faster than the torque being supplied from the engine. Used in many manual and automatic transmissions, overdrive gears effectively reduce engine RPM while at cruising or highway speeds, contributing to reduced engine wear and higher fuel efficiency.
Overhead Cam: A type of valvetrain arrangement which features the engine's camshaft mounted above the cylinder head and operating directly on the valve stem. This arrangement allows the valvetrain components to be stiffer and lighter, enabling the valve to open and close more rapidly and the engine to run at a higher RPM. (See also Double Overhead Camshafts.)

P

Panic Button: A feature on many GM remote keyless entry systems which allows the driver to activate an alarm by pressing a button on the personal remote keyless entry key fob.
PASSLock: A GM exclusive, PASSLock makes it virtually impossible to start the engine by breaking into the ignition lock or by hot-wiring. The engine will only start when the driver turns the ignition lock, automatically sending a code to the on-board computer system to start the engine. Should the code be incorrect, the fuel system is automatically disabled.
Piston: A metal component which fits into the cylinder. Power is created as the piston moves up and down by the burning of the air/fuel mixture, and transmitted to the crankshaft through a connecting rod.
Piston Ring: A spring-loaded metal ring positioned around a piston which presses outwards against the cylinder wall to provide a tight seal. This prevents oil from the crankshaft below the seal from entering the combustion chamber above the seal.
Platform: The basic understructure of a car, van or truck. Vehicles which look completely different in terms of styling and purpose may still be built on the same platform.
Powertrain (or Drivetrain): The group of components that transmit torque and speed to the driving wheels. This includes the engine, clutch, transmission, drive shafts, universal joints, differential gear and axle shafts.
Powertrain Control Module (PCM): A built-in computer which uses sensors to assess all relevant driving information and automatically adjusts the engine and transmission to the appropriate settings for optimum performance.
Pushrod: A rod moved by a cam to operate the valves in an internal-combustion engine, used in Pushrod engines (also known as Overhead Valve (OHV) engines).

Q

R

RPM: Revolutions per minute. Used as a unit of measurement for engine speed.
Rack-and-Pinion: A popular steering mechanism which incorporates a pinion gear working in tandem with a toothed bar (the "rack"), the ends of which are linked to the vehicle's wheels. When the driver turns the steering wheel, the pinion gear rotates and causes the rack to move from side to side, which then steers the wheels right or left.
Rear-Wheel Drive: See Drive.
Remote Keyless Entry System: A system which allows the driver to control the door locks and unlock the trunk or tailgate from up to 6m (20 ft.) away, using a key fob transmitter. May also include a Panic Button.
Residual Value: An estimate of your vehicle's worth at lease-end as set by the lessor for the purpose of calculating your monthly lease payment. Residual values vary by term, vehicle make and model, based on predicted rates of depreciation.
Resonator: A small component of a vehicle's exhaust system designed to help the muffler in quieting the engine.
Rocker Panel: The body panel which runs along the side of a car, immediately below the doors and between the wheel openings.
Roll (or "sway" or "lean"): The movement of a vehicle's body while in motion in relation to its idle state — particularly noticeable while cornering.
Roll bar: See Stabilizer Bar

S

SAE: The Society of Automotive Engineers. This professional organization sets standards for measuring horsepower and torque, as well as for many automotive products such as fasteners, lenses and hoses.
Satellite Navigation: Usually set in a dashboard, these systems use GPS (Global Positioning System – a satellite-based radio navigation system) to determine a vehicle's current position in order to help guide drivers to desired destinations. Newer DVD-based and Hard Drive Device (HDD)-based systems (such as those found in many GM vehicles) are amazingly accurate and helpful.
Seatback, Rear Folding: A rear seatback which can be folded down to access the cargo area, effectively adding storage space. The seatback is sometimes divided into two sections, either of which can be folded down while the other remains upright — allowing both additional luggage space and room for a rear passenger at the same time.
Second-Gear Start: A convenience feature found on some automatic transmissions which allows the vehicle to start from a stop position while in second gear. This manoeuvre permits a more controlled start with improved traction in slippery or winter conditions.
Security Deposit: A refundable dollar amount that you pay at the time of lease signing. This amount can be used by the lessor to pay for all or part of any excess kilometrage or excess use charges you may have at lease-end.
Sedan: Usually a car with a fixed roof and four doors.
Semi-Independent Trailing-Arm Suspension: An independent rear wheel suspension system which holds each wheel in place with the aid of a large, triangle-shaped arm which can pivot at two points. This system provides a stable and comfortable ride.
Sequential Fuel Injection (SFI): A precise method of fuel injection which injects the fuel at the exact beginning of each cylinder's intake cycle. Benefits include optimal engine performance and driveability, smooth idling, and better fuel efficiency and emissions performance.
Series (Tire): How a tire is numbered according to it aspect ratio. See Aspect Ratio.
Shock Absorber: An important part of the vehicle's suspension system which dampens the effects of road surface bumps while helping to keep the wheels in constant contact with the ground. Normally, this is accomplished with hydraulics, forcing oil through small internal passages in the shock absorber's tubular housing. Gas-charged systems are pressurized and designed to respond faster than ordinary shock absorbers by reducing hydraulic lag caused when oil meets air.
Side-Window Defogger: A small vent at the end of the dashboard or on the door which directs air towards the side window, helping to keep the glass clear of fog so that side mirrors are clearly visible.
Single Overhead Camshaft (SOHC): A type of engine featuring a single camshaft in each cylinder head to control both intake and exhaust valves. This system substantially improves the engine's ability to build RPM more quickly by eliminating pushrods and rocker arms normally found in other camshaft arrangements.
Solar-control Tinted Glass: Tinted glass with the ability to filter out as much as 50% of the sun's harmful ultraviolet and infrared radiation, helping to protect a vehicle's interior materials as well as reducing air conditioning load and cool down time. Also known as Solar-Ray^® tinted glass.
Soft-Ray Tinted Glass: Tinted glass which reduces glare and helps maintain a cool interior, but lacks the reflective properties to filter out ultraviolet rays.
Spark Plug: A device which creates a spark to ignite the air-fuel mixture in the combustion chamber. The spark plugs in many GM vehicles are platinum-tipped for extended life, requiring replacement only at 166,000 kilometres*.; * Maintenance requirements vary with use and driving conditions.
Spoiler: An aerodynamic device, normally mounted on the rear of the vehicle, which changes the direction of the air flow. Spoilers use aerodynamics to help keep the vehicle from lifting and to increase manoeuvrability (while giving the vehicle a more sporty appearance).
Sport Utility Vehicle (SUV): A vehicle which combines truck-type performance and engineering with an interior equipped to seat at least four passengers and provide comfort and safety features available in cars.
StabiliTrak^®: StabiliTrak is an electronic stability control system that uses computer software and directional sensors networked with a vehicle's steering, suspension, anti-lock braking (ABS) and traction control systems. When required, the appropriate brake is automatically engaged, helping to return a vehicle to the desired direction. StabiliTrak is standard on many GM vehicles.
Stabilizer Bar: A component of the suspension system which resists the vehicle body's tendency to roll as a result of uneven up/down motion between the wheels to which it is connected. Also called an anti-roll bar, Roll bar, tension bar or sway bar.
Steering Ratio: A predetermined ratio established for the steering gears to give the vehicle optimal steering capability. Usually, the lower the steering ratio, the quicker the steering response.
Steering, Variable-Assist: Any power steering system which provides varying degrees of assistance to suit specific driving needs and conditions. Maximum assistance is provided at low speeds, to help in parking and manoeuvrability, while assistance is reduced at higher speeds, such as highway cruising, to provide improved stability and road feel.
Steering, Variable-Ratio: A system using variable gear ratios which change as the wheel is turned to assist in steering. On straightaways, the gearing ratio is greater to provide a more stable feel. As the steering wheel is turned, the gear ratio becomes progressively smaller, requiring fewer turns of the steering wheel.
Supercharger: An engine-driven turbine which pressurizes the air-fuel mixture, driving it into the combustion chamber to produce enhanced power and torque.
Suspension: The component system which keeps the vehicle raised above the wheels. This includes springs, struts and/or shock absorbers and linkage.

T

Tachometer: An instrument which measures the speed of the engine crankshaft in revolutions per minute (RPM). Tachometers are usually found in a vehicle's instrument cluster.
Theatre Dimming: A system which allows a vehicle's interior lights to gradually fade out, rather than immediately switching off.
TheftLock^TM: A theft deterrent feature designed to render a sound system inoperable if stolen and placed in another vehicle. TheftLock is included with many GM sound systems.
Throttle-Body Fuel Injection: A type of electronic fuel injection in which the injector(s) is/are positioned in a central location inside a throttle-body housing. From this housing, a special valve regulates the flow of air through the intake manifold to increase engine performance.
Tilt Adjustable Steering Column: An adjustable steering column which allows the driver to manually tilt the steering wheel up or down, increasing comfort and control, and allowing for easier entry and exit.
Tire Pressure Monitoring System: A system that alerts drivers before tire inflation levels become too low or too high.
Torque: The amount of twisting effort exerted at the engine's crankshaft — what gives you that "pushed back in your seat" feeling as you step on the gas. Torque can be calculated in Gross and Net terms, Gross torque being the maximum amount of torque available by an engine operating with no accessories, and Net torque being the actual amount of torque available at the engine's flywheel with all of the engine's accessories, such as fan, water pump, generator, etc., in full operation.
Torque-Axis Mounting: A system which calls for mounting an engine on its true torque axis, thereby reducing engine noise, vibration and idle shake.
Torque Converter: A system of increasing torque with the addition of a third element called a "stator". This increase in torque, however, is achieved at the expense of efficiency.
Torsion: Twisting. A car body's torsional strength is its ability to resist twisting forces, such as the impact of a large bump encountered by a single wheel.
Traction Control: An electronic system which helps to control wheelspin during acceleration. When wheelspin is detected by the ABS sensors, the Powertrain Control Module is signaled, automatically reducing the engine torque and applying brakes to the appropriate wheel. A simpler system, managing engine torque only, is called an Enhanced Traction System.
Transaxle: Typically found in front wheel drive vehicles, the transaxle eliminates the need for a separate connecting drive shaft by combining the transmission and differential into one assembly.
Transmission: A combination of gears used to transfer engine power to the driving wheels through different gear ratios.; AUTOMATIC TRANSMISSION - Shifts gears up or down, according to speed and driving conditions, without the need for driver intervention. Shifting is controlled electronically or by hydraulic pressure.; MANUAL TRANSMISSION - Requires a driver to select and shift to the appropriate gear according to speed and driving conditions.; Both types of transmissions are further classified by the number of gear ratios they carry, i.e. 4-speed, 5-speed, 4-speed automatic with overdrive, etc.
Transmission Fail-Safe Feature: A safety feature allowing certain automatic transmissions to automatically select working gear ratios should one or more fail. This ensures the driver can maintain control of the vehicle.
Tri-Link Suspension: A fully independent rear suspension design featuring a series of round, tubular links to provide high stiffness for improved handling, as well as a series of rubber links to control noise.
Tuned Intake and Exhaust Systems: Efficient intake and exhaust systems which increase the flow of air-fuel mixture in, and exhaust gases out of the combustion chambers by providing the optimum shape, length and diameter of the components.
Tungsten-Halogen: A type of bulb, used in composite headlamps, which produces a whiter, brighter beam of light, while using less power than conventional headlamps.
Turbocharger: An exhaust flow-driven turbine which increases the air-fuel mixture entering the combustion chamber to produce enhanced power and torque. A supercharger delivers similar results, though mechanically driven by the engine's crankshaft.
Twilight Sentinel^TM: A system that senses outside light to adjust the headlights and daytime running lights to the proper setting. Also adjusts the intensity of the dash lights.

U

Unitized Construction: A type of body construction that provides structural strength and support for the vehicle's mechanical components without the need of a separate frame. Also called "unibody" or "body-frame integral" (BFI).

V

V-Type Engine: An engine layout characterized by a V-shaped double bank of cylinders. For instance, the designation V8 indicates an 8-cylinder engine with a V-shaped cylinder layout. (See L-Type engine for comparison.)
Valve: A device which enables or prevents the flow of a gas or liquid from one place to another by opening up or closing down. Most internal combustion engines use intake and exhaust valves to allow air-fuel mixture into the cylinders, and to exhaust burnt gases.
Valvetrain: The collection of parts that allow the valves to open and close, allowing fuel intake, compression and exhaust. These parts include the camshaft(s) and all related drive components along with the variety of parts that convert the camshaft's rotary motion into a reciprocating (up and down) motion at the valves.
Viscosity: The ability of a liquid, usually oil, to flow. Oil with a high viscosity is quite thick and flows slowly, while oil with a low viscosity is thinner and flows more readily.

W

Weight Distribution: A comparison of how much of a vehicle's total weight is supported by each axle or wheel. For instance, a typical front-wheel drive car carries 60% of its total weight on its front wheels and 40% on its rear wheels, giving it a front/rear weight distribution of 60/40. The conventional wisdom is, the closer the distribution is to 50/50, the better the handling.; This comparison is especially also important in trucks, affecting the service life of the frame, axles, springs, bearings and tires, as well as playing a key role in selecting the most appropriate vehicle for a job.
Wet-Arm Windshield Wiper/Washers: Wiper arms featuring built-in washer nozzles, to provide uniform distribution of washer fluid across the entire washed area of the windshield.
Wheel Speed Sensors: Critical to both the anti-lock braking, and traction and stability control systems, Wheel Speed Sensors measure the speed at which a vehicle's wheels are turning.
Wheelbase: The distance between the centres of the front and rear wheels.
Window Lock-out: A child safety feature which, when engaged, prevents passengers from opening or closing the power windows.

X

Y

Yield Strength: The maximum load that can be safely applied to a frame material without risk of permanent damage.

Z

*All-Season Tires may not meet all regulations for all regions.

Alphabetical Listing

AUTOMOTIVE 101