Mild Hybrid

A mild hybrid pairs a conventional combustion engine with a small electric motor and a modestly sized battery, typically operating on a 48-volt electrical system rather than the higher voltage systems used in full hybrids and electric vehicles. Unlike a full hybrid or plug-in hybrid, a mild hybrid's electric motor cannot power the wheels on its own; it exists purely to assist the combustion engine, supporting functions such as smoother and faster engine start-stop operation, brief torque fill during acceleration to reduce the sensation of turbo lag, and capturing energy through regenerative braking that would otherwise be lost as heat.

Because the electric motor and battery in a mild hybrid system are much smaller than in a full hybrid, they add relatively little weight and cost to the vehicle while still delivering a real, if modest, improvement in fuel economy, generally in the range of a few percentage points to around ten percent depending on the application. This makes mild hybrid technology attractive to manufacturers looking to meet fleet-wide fuel economy and emissions targets without the greater cost, weight, and complexity of a full hybrid or plug-in hybrid powertrain, and mild hybrid systems have become common across a wide range of vehicle segments, from economy cars to full-size trucks and performance models.

Mild hybrids are distinct from full hybrids in one key respect: a full hybrid can drive the vehicle on electric power alone for short distances at low speed, while a mild hybrid's electric motor works only in tandem with the combustion engine and never independently propels the car. This distinction is why mild hybrids are sometimes viewed as a lighter-touch, lower-cost stepping stone toward electrification rather than a fundamentally different way of driving, since the core driving experience remains much closer to a conventional gasoline vehicle than to a hybrid or electric vehicle.