10 used cars that depreciate the most A study by UsedCarExpert.co.uk to find the 10 used cars that have depreciated the most between December 2011 and May 2012 has revealed that premium models are no longer as resistant to depreciation as they once were. The website studied feeds from car dealers, auctions and car advertising networks to find the 10 cars whose values have dropped the most. A sample size of at least 100 each model was required, meaning that expensive mainstream cars feature heavily. Those who have recently bought a used luxury car, large 4x4 or sports car might want to look away now... Average used price in December 2011: £22,062 Average used price in May 2012: £19,097 Difference: -£2,965 (-13.44 per cent)