Glossary of Automotive Terms

Accessories

These can allude to extra options not usually included on base models. Can also indicate items controlled by either battery power including power steering, electric windows and air conditioning or by the car's engine.


All-Wheel Drive

Cars or trucks which have all-wheel drive have all four wheels being driven at the same time. Some systems are completely in operation at all times, while others only drive either the front or rear wheels under normal circumstances. Then, when the drive wheels start to lose balance, the computerized contros assigns power to the other wheels. All-Wheel Drive is not the same as four-wheel drive as 4WD vehicles can usually be placed in two-wheel drive mode, while AWD vehicles cannot.


Anti-Lock Braking System (ABS)

Vehicles equipped with ABS use electronic sensors located near each wheel to decide whether the wheels are skidding, or locked up while braking if the driver has slammed on the brakes. If the tires are skidding, the system very briefly releases the brakes to permit the tire to regain traction to the road, and most of the time, this helps the driver stay in control. The instantaneous capture and release of the brakes when ABS is activated frequently makes the brake pedal to vibrate.


Anti-Roll Bar

(Also referred to as "Sway bar" and "Stabilizer bar.") A steel rod that links the right and left suspension structure to the frame. This decreases body roll while cornering, which increases cornering stability. Most cars have anti-roll bars in the front but some have a rear one.


Brake Assist

Even though contemporary ABS systems do a good job of bringing a vehicle to a stop, a good number of drivers don't press the brakes hard enough in an emergency stop to make the most of the system. As a result, several automakers have included Brake Assist which automatically administers the complete brake force during a panic stop to slow the vehicle as rapidly as possible.


Catalytic Converter

Approximately the size of a small-scale muffler, the Catalytic Converter is embedded under a vehicle as part of the exhaust system. Inside is a special metal component that converts engine emissions into water vapor and carbon dioxide.


CFC-Free Air Conditioning

In place of CFCs that are detrimental to Earth's ozone layer, today's vehicles employ R-134a refrigerant which is CFC-free.


Coil springs

One of several types of springs used in suspension systems. Coil springs are built from a single piece of tempered steel wound into a cylindrical coil shape. Often employed in cars or SUVs.

Continuously Variable Transmission (CVT)

Unlike regular automatic transmissions, a CVT doesn't have gears to be changed. Rather, depending on how fast a driver wants to accelerate it uses two variable diameter cone-shaped pulleys with a steel belt strung between them to provide a constantly variable transmission ratio that renders a hydraulic torque converter extraneous and improves power application and fuel economy, while assisting with reducing emissions.


Crossover

Many of the newer, car-based SUVs that blend the offroading benefits of an SUV with the comfort and maneuverability of a car. They look like lowered SUVs or oversized station wagons.


Crumple Zones

Crumple Zones are sections of the front and rear of a vehicle that are designed to crumple during a crash so as to tas much energy as possible and keep the vehicle's occupants protected.


Curb Weight

This is how much an empty vehicle weighs without either passengers or cargo.


Daytime Running Lights (DRL)

A system that runs the headlights at a lowered strength so that oncoming drivers can more easily see your vehicle. This safety feature is really helpful on foggy days or when driving through shaded areas.


Double Overhead Cam (DOHC)

Two camshafts that are mounted inside each cylinder head instead of only one camshaft mounted in the engine block which was typical in older engine designs. With a DOHC arrangement, one camshaft activates the exhaust valves while the other works the intake valves.


Double Wishbone Suspension

This system features two sets of arms, one upper and one lower, both shaped like an A. The spindle that the wheel and tire mounts to is stuck in between the arms. Usually found in independent suspension setups.


Electronic Brake-force Distribution (EBD)

Another braking system that reduces stopping distances. It electronically disburses braking between front and rear wheels under stopping conditions not forceful enough to warrant activating the ABS braking system.


Electronic Fuel Injection (EFI)

Just about all new cars, trucks and SUVs use EFI. It is an electronically controlled fuel delivery system that delivers gasoline or diesel fuel into an engine.


Four-Wheel Drive

Trucks or SUVs that have 4WD have all four wheels being driven simultaneously. In addition, they usually have a 2WD setting that only drives the back wheels. Often comes with a low-range gear setting and locking differential for off-road or poor weather traction. See also: all-wheel drive and rear differential lock.


Ground Clearance

The space between the lowest part of a vehicle and the ground.


Horsepower and Torque

Horsepower is the rating of engine performance that allows an engine to maintain and increase the speed of a vehicle. Torque is what gets the vehicle moving in the first place. Vehicles like trucks that are required to tow heavy loads often have higher torque outputs compared to their peak horsepower figures. On the other hand, cars tend to have higher horsepower numbers than torque outputs because they are lighter and easier to get moving.


Independent Suspension (IRS)

A suspension setup where all four wheels move independently of each other. Formerly used almost exclusively on cars, IRS can now be found on some SUVs.


Knock Sensor

An electronic listening device that senses early signs of pre-ignition (also known as pinging or knocking) inside an engine's cylinders. The computerized system then delays when the ignition spark is delivered to the cylinder to reduce the possibility of engine damage.


Leaf Spring

One of several different kinds of springs used in vehicles. Composed of a series of flat steel plates sandwiched together to form a long, thin spring. Typically used in trucks and full-frame SUVs due to the superior strength of the spring.


Limited Slip Differential

Splits drive evenly between two drive wheels to maximize traction. Prevents one wheel from spinning while the other sits stationary. Unlike locking differential, a limited slip differential is ideal for paved roads.


Load-Sensing Proportioning and Bypass Valve

Varies braking force from front to rear depending on whether the vehicle is loaded or unloaded based on information received from load sensor. Helps maximize braking performance and reduce tire lockup.


MacPherson Strut Suspension System

A unit that combines both a shock absorber and a coil spring into one unit. Common front suspension setup on cars and car-based SUVs. Compact design makes them quite effective for the space used.


Micron Air Filter

Also known as a cabin filter. Much like the air filter in you home furnace, the Micron filter removes dust, pollen and other airborne particulates from air that's coming into your vehicle through the air conditioning, heater or vent system.


Multi-Valve Engine

Any engine with more than one intake valve and one exhaust valve. It's common for new engines to have 3, 4 or even 5 valves. Additional valves help an engine more efficiently take in the charge of fuel and air, while expelling the spent charge faster, thus increasing power and fuel economy, while reducing exhaust emissions.


NVH (Noise, Vibration and Harshness)

An auto industry term that refers to any kind of annoying occurrence that can negatively affect the ride and quiet of a vehicle.


Rack-and-Pinion Steering

A series of parts that connect the steering wheel shaft with the tires. Turning the steering wheel rotates a pinion, which meshes with a rack or lateral gear. The rack converts this rotating movement into a side-to-side motion. Each end of the rack is hooked to steering linkages that are in turn connected to the wheels. Rack-and-pinion setups are more precise than recirculating ball-type units.


Rear Differential Lock

An electro-mechanical system that locks both rear axles together providing them with equal drive power. For use in limited traction situations such as off-roading. Not for use on dry paved roads.


Seatbelt Pretensioners with Force Limiters

Safety innovation that automatically takes the slack out of the shoulder seat belt during a frontal impact to increase the effectiveness of the belt at protecting the occupant. The system then slowly releases the belt tension to lessen the impact forces transferred to the occupant.


Torque Converter

A fluid coupler used in automatic transmissions to transmit power from the engine to the transmission. The torque converter enables the engine to idle while the transmission is in gear without the engine stalling. It also helps the vehicle take off smoothly from a stop.


Traction Control

An electronic system that can sense traction loss at the drive wheels and decreases engine power or applies the brakes to regain traction.


Unibody

A unibody vehicle combines the body and frame into one unit. The frame is welded to the bottom of the vehicle's body which allows for stronger rigidity. Most light trucks and SUVs have a separate body and frame.


Valet Trunk-Locking System

A system that allows you to lock the trunk separately from the rest of the vehicle allowing a parking valet to drive your car without giving him access to the trunk.


Variable Power-Assisted Steering

Describes a steering system that's boosted depending on vehicle speed. On a sharp, slow corner assist would be increased while a car driving at high speeds would have reduced assist.


Variable Valve Timing

Computerized device that selects the best intake and exhaust valve opening and closing points during an engine's cycle. Maximizes low-rpm power output and fuel efficiency, while reducing.


Vehicle Skid Control (VSC)

An electronic system that keeps track of vehicle speed and direction then compares this data with the steering, braking and acceleration inputs. This information is then used in tandem with traction control and ABS systems to help driver keep control of vehicle during challenging driving conditions.


Ventilated Disc Brakes

Instead of solid steel disc brake rotors, ventilated rotors have an air gap drilled into the rotor that helps disperse excess heat that can collect in the rotor under severe braking such as stop and go traffic, or the continuous applyication of the brakes while going down a steep grade.