A Glossary Of Things

Powertrain: Types and layouts

  • Front-wheel drive (FWD) – Powertrain layout where the engine and transmission drive the front wheels only; common in small and mid-size cars. autozone

  • Rear-wheel drive (RWD) – Layout where power is sent to the rear wheels via a driveshaft and rear differential; common in performance cars and trucks. autozone

  • All-wheel drive (AWD) – System that can send power to all four wheels, often automatically, using a center differential or clutch pack. autozone

  • Four-wheel drive (4WD | 4×4) – Part-time or selectable system for off-road use with a transfer case that locks front and rear drives together. autozone

  • Hybrid powertrain – Combines an internal combustion engine with one or more electric motors and a battery pack to improve efficiency and/or performance. arm+1

  • Electric vehicle (EV) powertrain – Uses one or more electric motors powered by a high-voltage battery, with power electronics (inverter, DC–DC converter) and often a single-speed reduction gear.

Supporting systems and terms

  • Transfer case – Gearbox in 4WD/AWD vehicles that splits torque between front and rear axles and may provide low-range gearing. 

  • Transaxle – Combined transmission and differential unit, typical in FWD cars, mounted with the engine and driving the front wheels directly. 

  • Power electronics (EV) – Inverter, converter, and control modules that manage high-voltage power flow between battery and motor. 

  • Battery pack (EV | HEV) – High-voltage energy storage that supplies the electric motor(s); managed by a battery management system (BMS). 

  • Drivetrain – Often used interchangeably with powertrain, but technically the subset that delivers power to the wheels (transmission onward), excluding the engine/motor itself. 

 
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