•Peugeot Citroen invents technology for air car ready for the market by 2016 •'Hybrid Air' engine system runs on petrol and air, instead of electricity •Company predicts 'Hybrid Air' to achieve 117 miles per gallon by 2020 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...