In unveiling the Passat Estate TSI EcoFuel concept – a car powered by either natural gas or conventional petrol – at the Geneva Show, engineers have combined the seemingly contradictory virtues of performance and economy.

The Passat Estate TSI EcoFuel is powered by a 1.4-litre TSI 150 PS engine running on either natural gas or petrol.  The engine features both a supercharger and a turbocharger operating sequentially to provide relatively high power outputs from a small capacity engine.  In order to allow the engine to cope with the additional loading encountered through the burning of natural gas rather than gasoline, significant changes are made.  The valves, piston rings and the pistons themselves are all uprated to cope while the turbocharger has also been replaced with a smaller unit.  Controlling the switch between conventional fuel and natural gas is a new engine management computer.

The natural gas is stored in a trio of tanks with a combined capacity of 22 kg mounted beneath the boot floor.  This is supplemented by a 31-litre tank for conventional petrol. Between the two tanks the Passat Estate TSI EcoFuel is afforded a theoretical range of over 490 miles.

The result is a non-diesel vehicle that meets the Euro 5 standards, greater economy and lower emissions.  In addition, with a top speed of 130 mph and the capability to accelerate from 0 to 62 mph in 9.7 seconds, the Passat Estate TSI EcoFuel remains viable for everyday use.  In normal conditions the vehicle consumes 5.2 kg of natural gas every 100 km.

In mainland Europe the vehicle will be introduced in both saloon and estate bodystyles before the end of the year.  Sales of the vehicle in the UK are yet to be confirmed.