Auto Glossary

Damping is the motion of cushioning the vehicle's body movements in order to smooth the ride over bumpy roads and eliminate uncomfortable vibrations coming from the surface of the road.

Dynamic Brake Control (DBC) is a BMW developed active safety system which improves brake effectiveness during emergency braking. Vehicles equipped with the system use sensors to detect the speed and force with which the driver applies the brakes and then send this data to an ECU. If the ECU calculates that the driver intends to do an emergency stop using the criteria gathered from the sensors it will provide the maximum amount of pressure in the brake cylinders, in order for the car to stop in the shortest distance possible.

DCT is an automated transmission that uses two separate clutches for odd and even gear sets.

A differential is a device that can be used to do two mainly different things: either it can be used to transfer power from the transmission (or transfer gearbox in case of a 4WD vehicle) to the driving axle, or it can allow two wheels on the same axle to turn at different speeds, but using the same power.

A differential lock (or diff-lock) literally locks out the differential action, thus forcing the torque to be split equally between two wheels or two axles. Transforming two axles to work as one or two wheels to rotate as if on a single axle can help increase traction in off-road terrain or in a straight line while accelerating hard.

Disc brakes are the most common and also most effective means of stopping a vehicle. This type of braking system usually consists of a disc that rotates at the same speed as the wheel to which it is attached, straddled by a brake caliper. The caliper contains brake pads which are operated by one or more small pistons that squeeze against the surface of the disc to slow it down or even stop it. Compared to the drum version, disc brakes operate much more efficiently at high temperatures and wet conditions, basically by having a more complete design.

An internal combustion engine's displacement is defined as the total volume of the cylinders. More specifically, since pistons move up and down cylinders, the volume is defined by calculating the total air and fuel mixture an engine's cylinders can draw during one complete engine cycle (one revolution of the crankshaft). In most countries it is stated in cubic centimeters, liters or cubic inches.

Derived from the words "distance" and "electronic", Distronic is an advanced cruise control system found in some high-end Mercedes-Benz models. The main difference between a conventional cruise control system and Distronic is that - apart from keeping the vehicle on a steady speed - the technology is also using radar sensors to automatically detect and adapt to the speed of the car traveling in front. In its latest version, Distronic can use the data from the radar sensors to automatically accelerate or even bring the vehicle to a complete halt in case it detects changes in the speed of the vehicle ahead.

DOHC is a valve train layout characterized by two camshafts within the cylinder head. This means that there are two separate camshafts for inlet and exhaust valves, unlike SOHC (Single Overhead Camshaft) layouts where a single camshaft operates both inlet and exhaust valves.

An interior design that has separate and symmetrical areas carved out of the dash for the driver and front passenger; a retro look common to early Mustangs and 1963-67 Corvettes.

Downforce is the phenomenon when air pressure is pushing down on a vehicle at high speeds, thus enabling more stability and better traction. It is usually achieved by the use of spoilers and aerodynamic ground effects.

DPF is a device meant to remove the particulate matter from the exhaust fumes of a diesel engine.

The driveshaft (also known as propeller shaft or propshaft) transmits power from the engine through the transmission (or transfer gearbox in case of 4WD vehicles) to the differential.

Also known as the powertrain, the drivetrain describes all of the vehicle's components which are used to produce and transmit power to the drive wheels. In short, the engine, transmission, driveshafts, differentials and axle shafts are all part of the drivetrain.

Daytime Running Lights (DRL) are a new feature incorporated on some of the modern cars in order to insure better visibility for other drivers, which in turn would help prevent more crashes. They are usually comprised of normal high-beam headlamps with reduced intensity or low-beam headlamps and are deactivated the moment "normal" headlamps are turned on.

A drum brake is made of a drum-shaped housing (which is usually out of cast iron) that is attached to the wheel. Inside the drum there are usually two brake shoes curved around the interior that are forced into contact with the inner drum. The contact of the pads with the inner section of the drum housing provides braking. Drum brakes are very simple and generally very effective, except under heavy or hard use and under wet conditions, which is why they are less and less common on modern cars.

Dynamic Stability Control (DSC) is BMW's marketing name for the Electronic Stability Control, which uses the anti-lock braking and traction control systems to improve directional stability when cornering and intervening to help prevent or correct oversteer and understeer. Like any other stability control system, it helps the vehicle avoid skidding and loss of control by applying the brakes individually or by reducing the engine power.

Dynamic Stability and Traction Control (DSTC) is a sophisticated stabilization system from BMW which combines the DSC (Dynamic Stability Control) with the Traction Control system, thus essentially offering skid-free driving.