Automotive Glossary

At Consumer Guide we know shopping for a vehicle can be daunting. It's made even harder by the proliferation of gee-whiz and techno-gadgets available on cars, trucks and SUVs. To help you simplify things a bit, here is a glossary of common automotive innovations, some of which may not have existed the last time you bought a vehicle.

Adaptive automatic transmission
Some transmissions can "learn" and adapt to the driver's style, altering shift points and other transmission functions to produce the most efficient operation.

Adaptive Cruise Control

One step beyond cruise control, adaptive cruise control uses a radar sensor mounted in the front of the vehicle to maintain a safe cruising distance between your vehicle and the vehicle in front of you. Most systems allow you to set the interval (distance between vehicles) and will then accelerate and brake (within reason) to maintain that interval. In many cases, the systems can take into account hilly terrain and passing situations. All have the ability to act like regular cruise control, and they still require the driver to steer the vehicle normally. Some automakers refer to it as "intelligent" cruise control.

Air suspension
Instead of steel coil or leaf springs, some vehicles have a bellows-like unit at each corner that contains pressurized air. As a rule, air suspensions can produce a softer ride.

Adjustable suspension
Provides better ride or handling. A variety of systems are used to vary shock-absorber firmness. Some automatically sense road conditions and adjust shock-absorber settings accordingly. Others include a switch on the dashboard or console that allows the driver to adjust shock-absorber settings to provide a softer or firmer ride, or sharper handling.

Anti-lock Brakes (ABS)

Helps maintain control in emergency stops. Particularly useful on slick pavement. While the driver applies steady pressure to the brake pedal, the system automatically "pumps" the brakes many times per second to prevent wheel lock-up.

Antiskid system
Helps maintain control in fast turns. Works whether or not the brakes are applied. Sensors automatically apply individual brakes to prevent a sideways skid. Some systems also cut back on the throttle, slowing the engine. It's also known as an electronic stability system or stabilization program.

Automatic climate control
A heating and air conditioning system that adjusts itself as needed, to maintain a pre-set temperature.

Automatic transmission with manual-shift capability

Allows manual gear changes, when desired, in an automatic transmission. Functions as a traditional automatic transmission when left in Drive, but includes a slot in which the shift lever can be moved to change gears manually. Sometimes, buttons for shifting manually through the gears are located on the steering wheel. This affords some of the advantages of a manual transmission, such as greater control of engine speed for better throttle response, but eliminates the need for a clutch pedal.

Bluetooth capability
The ability of a radio system to work with Bluetooth wireless connectivity, to function in concert with a cellular phone.

Brake assist
Designed to shorten stopping distance in a "panic" stop. Applies full braking power even if the brake pedal is not fully depressed. Sensors gauge the speed at which the driver initially depresses the brake pedal and determine whether full emergency stopping power is warranted.

Continuously variable transmission (CVT)
Operates like an automatic transmission, with no need for a clutch pedal, but contains no gears. Instead, power is transmitted in a continuous flow from the engine to the drive wheels.

Curtain side airbags

Designed to cushion and protect occupants' heads. Located on both the left and right sides of the vehicle, curtain side airbags deploy from above the front and rear side windows in a side-impact collision. Advanced systems deploy the bags when sensors detect an impending rollover. The bags inflate within a fraction of a second and deflate after a few seconds. They also help shield occupants from broken side glass. In some vehicles with three rows of seats, the curtain airbags do not reach backseat occupants.

Dual front airbags
Designed to protect the driver and front passenger in a frontal collision. Mounted in the steering wheel hub and in the right side of the dashboard, they inflate and deflate within a fraction of a second. Most systems can judge the severity of an impact and determine whether a front-seat occupant is wearing a safety belt or is out of position. This allows them to adjust the rate of deployment to minimize injuries from the airbags themselves. Dual front airbags are required by law on all new passenger vehicles.

Dual-stage airbags

Front airbags that can deploy at either of two levels, depending on the severity of a collision.

Dual-zone climate control
Allows individualized control of heating and air conditioning. Most systems are adjustable for the driver and front passenger; others feature a third adjustment for rear passengers.

Electronic brake-force distribution
Operates in conjunction with ABS to balance the force applied to brakes at front and rear wheels. Can prevent over-braking, improve brake-pad life, reduce "brake fade" caused by excessive heat, and ensure peak braking efficiency in all conditions.

Hybrid powertrain

A propulsion system wherein a gasoline engine and electric motor work in concert. In some hybrid systems, electric operation is dominant; in others, the gasoline engine dominates. Only a few hybrid vehicles are available, but they promise greater fuel economy and reduced emissions.

Lane-departure warning system

Issues a warning when the vehicle edges off course and reaches the highway lane markers.  Introduced on the 2005 Infiniti FX and available on the 2006 Infiniti M45, the system developed by Iteris can detect lane dividers even in rainy weather. It delivers a noticeable sound when the vehicle starts to move into an adjacent lane, whether due to inattention, drowsiness or distraction.

MP3 capability
The ability of a radio to play computer-generated MP3 music, as well as CDs and/or cassettes.

Navigation system

An electronic map combined with route instructions, usually displayed on a dashboard video screen. The system communicates with a satellite to display, on the screen, the vehicle's geographic location and direction of travel. Most systems let you input a destination using a keypad. A computer then calculates the best route and issues audible and visual directions to reach that destination. A few navigation systems lack a map, but provide vocal instructions. Some new systems operate with voice recognition, and are able to "understand" addresses and other oral instructions. Navigation systems are usually optional, though some luxury models have them as standard equipment.

Overhead-cam engine
In this configuration, the camshaft that drives the valve is located atop the engine rather than down inside. Engines with a dual-overhead-cam configuration have two separate camshafts rather than one.

Oversteer and Understeer

Any serious race fan knows the difference between "understeer" and "oversteer," but ask for a description and they might get confused. Most front-wheel-drive cars will "understeer" ("push" or "be tight") at the limit of adhesion, the point when the wheels lose their grip on the road. This condition is most noticeable in rain or snow. As you enter a corner and begin to turn the wheel, the car may try to go straight instead; and the harder you steer into the turn, the more the vehicle wants to continue to drive straight. You can help lessen the effects of understeer by lifting off the gas slowly and slightly applying the brakes. This will transfer more weight to the front wheels, allowing them to get more traction.

Most high-performance rear-wheel-drive cars will "oversteer" or become "loose" if you enter a turn too fast. The effect is similar to "doing donuts" in the high school parking lot after a snowfall. Oversteer is much more dangerous and difficult to correct. You have to first steer in the opposite direction to limit the slide of the car, and then you must be very gentle with the throttle and brakes to prevent the vehicle from going into a "snap" or violent spin.

Vehicle skid control systems can reduce understeer or oversteer, but they cannot change the laws of physics. Either way, it helps to know what to do when your car is at the limit of adhesion so you will react quickly and instinctively. It could save you thousands in a repair bill, or even your life.

Real-time traffic information
Introduced on the 2005 Acura RL, this system can work with satellite radio to warn the driver if traffic conditions ahead are troublesome. It can then determine if an alternate route might be a better choice.

Rear obstacle warning system

Alerts the driver to unseen objects behind the vehicle when backing up. Sensors mounted in the rear bumper detect the presence of nearby objects. A tone or warning lights signal the distance to these objects. Some systems also warn of nearby objects in front.

Rear-seat entertainment system

Allows rear-seat passengers to view video. An option most often offered on mininvans and SUVs. Earlier entertainment systems played VHS video tapes, but most of the current ones play DVDs. Most have a screen that drops from the ceiling behind the front seats; others locate the screen near the floor between the front seats. The video/DVD player is mounted low in the dashboard or between the front seats or in the front center console. (A few vehicles, such as the Toyota Land Cruiser and Lexus LX 470, can play DVDs on their navigation system's dashboard screen, but only when the vehicle is standing still.) Most systems allow front-seat passengers to listen to a separate audio source while those in back view videos. Remote controls for the video/DVD player, wireless headphones, and video-game ports and controls are typical accessories.

Satellite radio
Two systems, XM and Sirius, provide radio reception via satellites rather than the customary broadcast method. Each service charges a monthly fee for delivering a large number of entertainment channels. Satellite-ready radios are standard in some vehicles and optional for many more.

Side airbags
Designed to protect occupants in a side collision. Some side airbags are shaped to provide protection for just the torso, others for both the torso and head in a side collision. Some are mounted in the side of the seat backrest. Others are in the door panel. The bags inflate and deflate within fractions of a second. Side airbags can be furnished for both front- and rear-seat occupants.

Side-curtain airbags
See "Curtain side airbags"

Stability-control system
See "Antiskid system"

Traction control
Helps limit tire slip in acceleration on slippery surfaces. Sensors determine if the wheels that are receiving power have lost traction. The system automatically "pumps" the brake to those wheels to keep them from slipping. Some systems also reduce engine power to the slipping wheels.

Turbocharging
Turbochargers make use of exhaust gases to compress the air that enters the engine, which increases its potential power output.

Variable valve timing
Using computer control, VVT alters the opening and closing of the engine's valves automatically to produce the greatest level of efficiency. Ordinary engines have fixed valve operation.

Voice recognition
Quite a few climate-control and other systems can respond to vocal commands. These systems are expanding into navigation systems as well. In Honda's redesigned 2005 Odyssey, for instance, the computer can understand a destination stated orally by the driver and calculate a route accordingly, with no need to use a keypad to enter a street or number.

Xenon headlights

Also known as "high-intensity-discharge (HID)" and "bi-xenon" headlights. Standard on some vehicles and optional on others, they provide a brighter and more effective beam. On a few vehicles, the headlights can move laterally in concert with the steering wheel to illuminate the road ahead even in a curve.