If you have ever grimaced at your petrol bill and dreamed of a car that runs on fresh air, your prayers are about to be answered.
French car giant PSA Peugeot Citroen believes it can put an air-powered vehicle on the road by 2016.
Its scientists say it will knock 45 per cent off fuel bills for an average motorist. And when driving in towns and cities costs could be slashed by as much as 80 per cent because the car will be running on air for four-fifths of the time.
The system works by using a normal internal combustion engine, special hydraulics and an adapted gearbox along with compressed air cylinders that store and release energy.
This enables it to run on petrol or air, or a combination of the two.
Air power would be used solely for city use, automatically activated below 43mph and available for "60 to 80 per cent of the time in city driving".
By 2020, the cars could be achieving an average of 117 miles a gallon, the company predicts.
The revolutionary new 'Hybrid Air' engine system -- the first to combine petrol with compressed air -- is a breakthrough for hybrid cars because expensive batteries will no longer be needed.
The system will be able to be installed on any normal family car without altering its external shape or size or reducing the boot size, provided the spare wheel is not stored there.
A company spokesman said "We are not talking about weird and wacky machines. These are going to be in everyday cars."
Peugeot, which unveiled its prototype on Tuesday, envisages introducing it in smaller models such as the 208 at first.
For more than two years, 100 elite scientists and engineers have been working on the air-powered car in top-secret conditions at Peugeot's research and development centre at Velizy, just south of Paris.