Jessica Ennis wearing her big tee
Jessica Ennis offers her own simple tips that every driver can follow to start benefiting from lower carbon and lower cost journeys.
The World Champion is backing a major initiative from BP Target Neutral, the official carbon offset partner for London 2012, to help motorists do their extra bit for the environment. 
Her tips have increased driving efficiency by as much as 10 per cent.
Such things she has done include, swapping her skin-tight running vest for a giant t-shirt to highlight the effects of extra drag from driving with your windows down.
She also tried running with a heavy bag on her back to show that extra weight in the boot means extra emissions and fewer miles per gallon.
She says: "I'm going on a lower cost and lower carbon journey to London 2012 and I want to encourage drivers everywhere to do the same."
Next, she and her support team are going to learn and put into practice the Eco-driving techniques that can help to cut fuel bills by hundreds of pounds each year and considerable reduce C02 emissions.
She adds: "I've realised that bodies and engines both need looking after to give their best. It's what's inside that counts ofcourse."
Femalefirst Taryn Davies
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