IN THIS FEATURE Performance and efficiency Parallel hybrid system Different modes for different driving styles Outperforming conventional engines... The biggest challenge

In contrast to Toyota's petrol-electric hybrid, which uses a split transmission and a bespoke gearbox, Peugeot has opted for a parallel hybrid system. This approach keeps costs down by allowing existing PSA components - such as the gearbox - to be used, but it makes it more difficult to harmonise the operation of the two powerplants. Peugeot acknowledges that if the car is to be a commercial success, it must offer a smooth transition from electric to diesel power and visa versa.

The PSA system combines the familiar 90bhp, 1.6-litre HDi engine with a 23kW electric motor. Both are located under the bonnet, together with the car's electronic brain. The battery pack used to power the electric motor is situated under the boot floor, where the spare wheel would normally be found. The hybrids will use run-flat tyres, so luggage space is unaffected.

Battery back is situated under the boot floor

Independently verified statistics lend weight to Peugeot's argument. The C4/307 Hybride HDi's achieve an EU average consumption of 83.1mpg, which represents a 28% improvement on the standard HDi. The Prius manages 65.7mpg and emits more carbon dioxide - 104g/km versus 90g/km for the C4/307.