Automotive engineers name the posts or “pillars” that support the roof in alphabetical order, working from front to rear. The A-pillar supports the windshield and the front of the roof.
Acoustic Control Induction System (ACIS)
Different engine speeds demand different airflow rates. The ACIS provides the best of both worlds: a long flow path for low engine speeds and large throttle openings, and a short flow path for small throttle openings and higher engine speeds. By giving the engine what it wants, when it wants it, you benefit from more power and better fuel economy.
Acoustic Noise-Reducing Front Windshield
This windshield is essentially a sandwich consisting of a thin (3.8 to 5.2 mm) layer of polyvinyl butyral (PVB) bonded between two sheets of glass. By incorporating the polyvinyl layer, an acoustic noise-reducing windshield actually weighs less than a tempered glass windshield of similar thickness. The PVB insulator helps dampen vibrations and reduce noise, and is “tuned” in many respects to absorb chassis vibrations and specific sound waves for a quieter interior environment.
Active Front Headrests 
These headrests are designed to optimize headrest position during certain types of rear-end collisions. When a vehicle is struck from behind, the force of the collision causes the seat to move forward, while the collision force causes the occupant’s body to move rearward. This combination of movement tightens a vertical cable within the seat, and because the cable is attached to a pivot point below the headrest, tension on the cable causes the headrest to move slightly up and forward. This pivoting action helps reduce neck injuries in certain types of rear-end collisions.
Active Traction Control (A-TRAC)
A-TRAC is a four-wheel-drive (4WD) traction control system with two levels: TRAC (on-road), and A-TRAC (off-road). Both use a combination of braking force and reduced engine power to restore traction, but A-TRAC doesn’t reduce power to the same extent. When a drive wheel begins to spin, the system compares the speed of all four driven wheels, then uses ABS to slow the spinning wheel. Engine power is reduced, and power is simultaneously transferred to a non-spinning wheel on the same axle (or the opposite axle when both wheels on the same axle have lost traction).
Adaptive Variable Suspension (AVS)
There are shocks, and there are adjustable shocks–and then there’s AVS. This system uses a group of sensors and an electronic control unit to continually adjust the firmness of each wheel’s shock absorber for optimum ride quality. The driver can adjust the overall ride firmness with a control switch.
Adjustable Power Liftgate
Automatic remote opens and closes your liftgate door with the push of a button. Liftgate can be programmed to open to your preferred height.
Adjustable Shoulder Anchor
Ever had a shoulder belt that came uncomfortably close to your neck or seemed to slip off your shoulder? Whether you’re small or tall, this feature helps you position the seatbelt so it fits you properly. The adjustable anchor mounts on a body pillar and adjusts vertically, allowing you to adjust the belt to cross the shoulder and chest between your neck and arm.
Advanced Parking Guidance System 
Your virtual co-pilot. It’s a clever system that can help you maneuver the vehicle when parallel parking or when backing into a parking space.
Advanced Technology Partial Zero Emission Vehicle (AT-PZEV)
The California Air Resources Board (CARB) uses various classifications to identify the emissions levels of vehicles. As clean exhaust goes, an AT-PZEV comes closest to a Zero Emission Vehicle (ZEV). The primary difference between a Partial Zero Emission Vehicle (PZEV) and an AT-PZEV is that the latter vehicle uses a type of technology that is advancing toward zero emissions.
Like a dam diverts water, an air dam redirects and smoothes the flow of air under the vehicle so the drivetrain, suspension and other underbody components don’t create as much wind resistance. That result is better fuel economy and improved stability.
Part of the emissions control system, air injection introduces fresh air into a hot exhaust manifold, which allows excess hydrocarbons and carbon monoxide to be burned before they enter the catalytic converter in the exhaust system. Igniting the unburned emissions creates cleaner exhaust and allows the catalytic converter to work more effectively. However, modern engine control systems are reducing the levels of hydrocarbons and carbon dioxide to a point that air injection will soon be unnecessary.
A general-purpose tire for cars, minivans and 4WD trucks that’s designed for a wide range of on-road driving and weather conditions.
A general-purpose SUV and pickup truck tire designed for the street, but engineered to withstand off-road conditions.
All-Wheel Drive (AWD)
Bring on the rain, sleet and snow–AWD is designed for road conditions that make other cars cringe. This on-road, all-weather drive mode delivers power to the front and rear axles but still allows the vehicle to maneuver smoothly on dry pavement thanks to a center differential. The center differential distributes power to the front and rear axles (at varying percentages according to traction needs) and also allows the axles to turn at different speeds when the vehicle is cornering, unlike a part-time four-wheel-drive system.
The engine battery is a bank in which to store energy; the tireless alternator is what supplies the juice. When the engine is started, a crankshaft-driven belt spins the alternator, which generates AC (alternating current) power to maintain a full charge on the starter battery and supply electrical power to a vehicle’s subsystems.
Aluminum Alloy Block and Cylinder Head
Lighter is better. Instead of the heavy cast-iron material used in the past, Toyota engines combine the long-term durability of iron cylinder liners in the block with the advantages of lightweight aluminum alloy in the engine block and cylinder head(s). A lighter engine means the vehicle’s steering, suspension, chassis and tires carry less weight, which translates into better ride, handling and responsiveness. Aluminum alloy also dissipates heat efficiently, which enhances engine performance.
Aluminum Alloy Wheels
A nice set of wheels completes the look of any vehicle. Made from a mixture of aluminum and other metals, aluminum alloy wheels are popular because they can be cast or forged in a variety of purposeful but sculptural forms to accent a vehicle’s exterior design. Aluminum alloy wheels are not only attractive, they are also lighter than comparably sized steel wheels, which can enhance vehicle performance by reducing unsprung mass (weight that is not carried by the suspension).
Simple but effective and very easy to read, these gauges are the traditional round instruments with a rotating pointer and printed faceplate used in/on an automotive dashboard. Some examples include the speedometer, tachometer and coolant temperature/oil pressure gauges.
Anti-Lock Brake System (ABS)
A skidding vehicle is hard to control–and that’s why ABS was invented. ABS uses magnetic wheel-speed sensors and a computer to monitor all four wheels while a vehicle is in motion. When the brakes are applied, and a wheel (or wheels) begins to decelerate faster than the others, the system recognizes this condition as the prelude to a skid. In response, the system rapidly pulses the brake at that wheel until it begins to roll at the same speed as the others and simultaneously maintains brake pressure on the wheels with better grip so there’s no skidding.
If you’ve ever locked your keys in your car (who hasn’t?), you’re going to love this feature. Used on vehicles with power door locks, it prevents the front doors from being locked if the key is in the ignition and either or both of the doors are open.
Oil changes are a fact of life–or are they? World Standard Automatic Transmission Fluid (ATF-WS) is a low-viscosity synthetic transmission oil that can, under normal use, be used for the entire service life of the transmission. That means fewer hassles and lower maintenance costs for the owner, and less waste in our environment.
Atkinson-Cycle Gas Engine
Named after its inventor, James Atkinson, this engine uses a later intake valve closing event than a traditional four-cycle engine, which effectively shortens the compression stroke and reduces pumping losses. This makes the engine more efficient but less powerful than a traditional four-cycle engine–particularly in terms of torque. However, when a high-efficiency Atkinson-cycle engine is teamed with a high-torque electric motor (as is the case with the Toyota Prius hybrid), the performance trade-off is practically eliminated.
It may sound like something psychedelic, but it’s actually a second-level, low-speed traction control feature on some 2-wheel-drive (2WD) trucks and SUVs. The first level, Traction Control, is designed to reduce drive-wheel spin. The key difference in the activation of Auto LSD is that, along with brake application to a spinning wheel (which helps engage a non-spinning wheel), Auto LSD also allows engine power to spin the drive wheels faster than the non-drive wheels. This comes in handy on boat ramps and when driving in modest off-road terrain, where some wheel slippage is desired.
Auto-Dimming Rearview Mirror
When bright lights are behind you, this mirror can be your best friend. It uses two layers of glass with an electrochromic layer between them that changes color when a built-in sensor detects bright headlight beams. This dims the mirror and helps reduce glare.
Auto-Dimming Sideview Mirror
Integrated with the auto-dimming rearview mirror, these sideview mirrors also use two layers of glass with an electrochromic layer between them. When the built-in sensor detects bright headlight beams, all three mirrors (rearview and both sides) dim to reduce glare.
Automatic Climate Control
A true “set it and forget it” feature that incorporates a thermostat, automatic fan control and automatic vent selection to keep interior temperature exactly where you want it.
Automatic Disconnecting Differential (ADD)
Helps shift a four-wheel-drive (4WD) vehicle into and out of 4WD by disengaging or engaging the front drive shaft (via the left front half shaft) without the need to unlock or lock the axle hubs.
Automatic Height Control (AHC)
Used on the Toyota Land Cruiser, Automatic Height Control (AHC) works in partnership with Toyota Electronically Modulated Suspension (TEMS). AHC is a hydraulic system that allows the driver to raise the suspension to negotiate rugged off-road terrain or lower the suspension to make it easier for passengers to climb in and out.
Automatic High Beam System 
Turn your highbeams on and leave them on–this system does the rest. With the headlight switch in “Auto” mode and the lamps on high beam, a small camera located in the front of the rearview mirror is designed to detect the headlights of an oncoming vehicle and can automatically switch the headlights to low beam, then back to high beam once the vehicle has passed. The system is also designed to detect the taillights of a vehicle in front of you and switch to low beam, then back to high beam when the vehicle turns off the highway or is passed.
Automatic Locking Front Hubs
The best invention in four-wheeling since the winch. When a vehicle with part-time 4-wheel-drive (4WD) is shifted into 4WD mode, the axles automatically “lock up” in the differential, providing engine power at each front wheel. Old-style manual hubs were mechanical systems that required the driver to get out of the vehicle and turn a switch on each front wheel before they could be driven by engine power.
Automatic Locking Retractor (ALR)
A great feature for parents, an ALR can maintain a fixed seatbelt length, making it possible to secure a child seat without using a seatbelt locking clip. ALR is activated by pulling the shoulder belt all the way out, then letting it retract to the desired length before buckling the child seat in place. Unbuckling the belt and allowing it to fully retract deactivates ALR. Remember: Never use a rear-facing child restraint seat in the front passenger seat. Children should always be secured in the rear seat.
Automatic Sound Levelizer (ASL)
Keep your eyes on the road, your hands upon the wheel. ASL will adjust your tunes to the perfect volume. Used in audio systems, an automatic sound levelizer automatically adjusts volume and tone in accordance with vehicle speed. As speed increases, so does volume to compensate for ambient sound in the vehicle’s cabin. As the vehicle slows down, there is less ambient noise, so volume is reduced.
Automatic Transmission Shiftlock
This safety device requires that the ignition be in the On position and the brake pedal be depressed before the transmission lever can be moved out of Park. The shiftlock prevents a car from being put into Drive or Reverse and accelerating inadvertently.
Automatic Transmission TOW/HAUL Mode
Designed for those occasions when you use your truck like a truck. An available feature on the Toyota Tundra’s 6-speed automatic transmission, TOW/HAUL mode changes the shift logic of the transmission so it selects and holds lower gears during acceleration and deceleration to improve towing performance. With TOW/HAUL engaged, the transmission doesn’t “hunt” (awkwardly down-/upshifting), especially on mountain roads while towing or hauling a heavy load. Acceleration, downhill engine braking, pulling power and cruising comfort are also improved.
Auxiliary Audio Jack
Connect your iPod® or similar device with this handy auxiliary audio jack (a female mini-jack) in a Toyota audio system. The audio jack accepts 3.5 mm audio plugs, the same size typically used for headphones. And because they’re small and easy to place, audio jacks can be located on the faceplate of the audio head unit, nearby on the instrument panel or in the center console. Rock on!
Auxiliary Engine Oil Cooler
When you’re towing or hauling heavy loads, engine oil temperatures can soar, reducing the oil’s viscosity and lubricating effectiveness. The available Tow Package on Tundra 5.7L V8 models includes an auxiliary engine-oil cooler, which is mounted between the engine block and oil filter. This fluid-to-fluid type cooler uses engine coolant to reduce the temperature of the engine oil as it passes through the unit.
Auxiliary Power Steering Fluid Cooler
Most of the time, your steering system really doesn’t have to work that hard. But during repeated steering inputs, such as driving off-road or parking a heavy trailer, the power steering fluid can overheat. That’s why an auxiliary cooler is standard in selected tow packages. This U-shaped fluid-to-air cooler reduces and maintains the temperature of the power steering fluid, and looks like a mini-radiator with cooling fins along the tube to dissipate heat. It is usually located near the engine radiator with delivery and return lines to the pump.
Auxiliary Transmission Fluid Cooler
Hot automatic transmission fluid cooks gaskets and seals, shortening the service life of the transmission. The auxiliary transmission fluid cooler (usually part of a truck’s towing package) is an air-cooled heat exchanger located near the radiator, where it is always exposed to incoming air. This helps the unit deliver consistently cooler fluid back to the transmission, which keeps fluid temperature in check when towing or hauling heavy loads.
AWD With Active Torque Control
When the road is slick, muddy or icy, this system’s got your back. It automatically shifts from 2WD to 4WD when a drive wheel slips. If the vehicle is primarily FWD, the system will engage the rear axle for extra traction, and vice versa. Active torque control systems allow the vehicle to drive in fuel-saving 2WD until a drive wheel slips, but instead of requiring that the driver shift into 4WD, the system shifts automatically.
No, not the lead singer of a heavy metal band. It’s a shaft on which a wheel revolves, or which revolves with the wheel. It’s also the word used to describe a solid beam that connects the two rear wheels of the vehicle, i.e., the rear axle. Axles help support the vehicle and, depending on the drivetrain configuration, may also transmit torque to the drive wheels.
Don’t speak dashboard? Check our indicator glossary to see what your vehicle is saying.See Indicators