Auto Glossary

A half-shaft is an articulated, rotating shaft used in independent suspension systems to transmit power from a differential to a drive wheel.

Hardtop is an automotive term which usually describes a rigid (sometimes detachable or even retractable) vehicle roof.

A hatchback is a type of automobile layout, consisting of a passenger cabin which includes an integrated cargo space, accessed from behind by a hatch or a flip-up window - which is usually counted as a 3rd or 5th door. Hatchbacks are also often called three-doors (two entry doors and the hatch) or five-doors (four entry doors and the hatch) cars.

The hauling capacity is the maximum amount of weight - including driver, passengers, options, accessories and luggage - that can be carried by a vehicle, according to the manufacturer.

HDi is PSA Group's marketing name for their range of common rail diesel engines.

High Intensity Discharge (HID) headlamps use the light of a plasma discharge arc to generate light. Each lamp contains a HID light source, electronic ballast, an optical reflector and lens, which can give the headlamps low or high beams by changing.

A vehicle with a high center of gravity will exhibit more body lean in turns and will be less stable, therefore making it more likely to roll over than a vehicle with a lower center of gravity.

Operating via the ESP (Electronic Stability Programme) longitudinal acceleration sensor when first gear is engaged and both clutch and brake pedals are pressed, the ECU maintains front brake calipers pressure for a few seconds after the brake pedal is released to eliminate the risk of rolling backwards and ensures a smooth getaway uphill.

A high-occupancy vehicle lane is a traffic lane reserved exclusively for the vehicles with at least one passenger aside from the driver. Alternate names: carpool lane, 2+ lane, transit lane, T2 lane, T3 lane.

Horsepower is a measure of the rate at which work can be done. Historically, it was derived from the ability of the average horse to carry a weight of 100 pounds over 330 feet in 1 minute, which became the equivalent measurement of one horsepower.

HVAC is the general term used to describe all of a car's heating, ventilation and air conditioning functions.

Hybrid radio is a system that combines radio and internet (IP) broadcast technology.

Hydraulic pressure used to maintain valve clearance that eliminates the need for valve adjustment and minimizes maintenance; many V6 and V8 powered automobiles have hydraulic valve adjusters.