Peugeot is working to make its HybridAir technology available for its road cars. The technology uses compressed air to boost a small capacity petrol engine and can operate in zero emissions air mode, with compressed air used to drive the hydraulic motor.

The system can also operate in petrol-engine-only mode, or petrol and air altogether. The compressed air tank is refilled by a hydraulic pump under deceleration or braking.

The technology could lead to production cars averaging 100 mpg UK (2.8 l/100km). The automaker will only be bringing the tech to its road cars sometime in 2015.

The HybridAir technology could bring an average fuel economy of 2.9 l/100km and CO2 emissions of 69g/km. That would be a serious improvement over the most efficient 208 in the range today, the 1.4 e-Hdi, which emits 87 g/km.