At what speed do hybrid cars switch from battery power to petrol power?

Electric motors are more efficient at slower speeds and petrol at higher speeds, but most of all when they work together.

22nd July 2009
At what speed do hybrid cars switch from battery power to petrol power? (Getty)

2012 Toyota Prius PHV, 'Plug-in Vehicle' prototype on display during the Green Drive Expo in Richmond, California © Kim Kulish/Corbis via Getty Images

Asked by: Julie Blakemore, Hereford

In a hybrid car, electric motors are used most when they're travelling at slower speeds around town. Petrol is more efficient at high speed, so the conventional engine is in charge on the motorway. For much of the time, however, the engine and electric motors run together with the car's power control unit, varying the relative amount of drive from each. So there's no set point where electric power switches off and petrol kicks in.

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