Auto Glossary

OHC is a type of piston engine whose camshaft is placed above the pistons and combustion chamber. This allows for a more direct control over the valves compared to other types of engines.

OHV is a type of piston engine with the valves fitted above the combustion chamber, in the cylinder head. Their design is simpler and has several advantages over other types of engines, including smaller size, and simpler driveshaft system.

The Occupant Position Detection System (OPDS) uses sensors to calculate passenger height and position. If a child should lean into the airbag deployment path, the sensor will prevent the side airbag from deploying and subsequently injuring the passenger.

Overdrive is a term which describes a transmission gear that reduces the power output needed to maintain the driving speed, therefore improving fuel economy.