Heptathlon Jessica Ennis and Paralympian Stef Reid have taken part in an eco-driving test.
In the computer-controlled test, Jessicas performance was compared to an expert driving the same car on the same route. Not only did the expert use much less fuel, but they were faster too.
The data from Jessicas 21 minute drive showed that over a year she would spend 1120 more on fuel than the expert, while also emitting an additional two tonnes of CO2.
Stef Reid was six minutes slower than the expert (who took 19 minutes to complete the course) but used 25% more fuel. Over 12,000 miles, Stef could save up to 455 and emit 780kg less CO2.
Jessica Ennis said: 'Efficient driving is about being smooth, safe and anticipating the road ahead. Ive learned not to accelerate too hard, not to over-rev and when slowing down to coast in gear with your foot off the accelerator.
'Im supporting a way of reducing my carbon footprint and saving money at the same time called Reduce, Replace and Neutralise. That means starting to do things such as learning to drive more efficiently, replacing fuel with a kind that helps the engine run more efficiently and offsetting the remaining carbon emissions.'
A new online carbon calculator that enables everyone to calculate and offset the carbon emissions from their travel has been launched by BPs not-for-profit programme, Target Neutral.
Visit www.bptargetneutral.com to find out more and to see Jessica and Stef taking their test.