BMW i8 review - engine and gearbox

While BMW won’t thank us for saying so, the three-cylinder TwinPower 1.5-litre engine in the i8 is essentially a heavily reworked version of the unit found in the base-model Mini Cooper.

We say reworked, because it generates 228bhp and 236lb ft of torque. This is then combined with an electric motor on the front axle, which produces 129bhp and 184lb ft.

As if the powertrain wasn’t complicated enough, 11bhp of hybrid drivetrain is generated by the starter motor, which also serves to torque-fill where the petrol engine is still spooling up its turbo. 

The complicated drivetrain demanded an equally ingenious transmission. Essentially, power from the petrol engine is transferred to the rear-wheels using a six-speed auto and the front handles the electric motor using a two-stage automatic box. The driver controls the six-speed either by leaving it in auto mode or via the shift paddles on the steering wheel.

In Eco mode, the gearbox does as you’d expect, shifting up at just the right moment to achieve maximum efficiency. Switch to Sport however and it’ll hold gears a lot longer. Shifts aren’t double-clutch gearbox quick, but they’re more than fast enough.