By 2007, British motorists will have lost an estimated £20bn on the value of the 2.58m new vehicles bought this year, according to pricing guide, WiseBuyer’s.

Nearly 60% of the estimated £35bn spent in 2004 will be lost, thanks to depreciation in the first three years of ownership.

"Depreciation on some models is simply dire, almost £35,000 over three years for a Mercedes S500, or just dismal - £8,000 lost on a Ford Focus 1.6 Zetec," says Nic Barfield, editor of WiseBuyer’s.

With a top-end model like the Mercedes S Class, depreciation adds up to £1.16 per mile over the car’s first 30,000 miles or over 80% of total ownership costs. And on the Ford Ka, it accounts for 15p per mile – or 55% of the overall 27.5p running cost per mile travelled.

WiseBuyer’s researchers compared depreciation, servicing, insurance, and fuel consumption on five 1999 T-registered cars that are still available as new models today. Their forecourt prices ranged from £2900 (Ka) to £30,000 (S Class), against £7,000 to £63,000 for the equivalent new model.

A used Rover 75 2.5 Connoisseur SE saloon produced the biggest percentage saving: 41p per mile for the used car, against 78p from new – almost halving overall running costs. The only car that came in under the 20p per mile barrier was the T-reg Ka 1.3, at 19p. But the Focus 1.6 Zetec, proved its worth as a used car choice, with costs of only 24p/mile (against 42p/mile from new).

Model Cost per mile for a USED 99T Cost per mile for a NEW 04/54
Ford Ka 1.3 18.8p 27.5p
Mercedes S Class S500 84.9p 142p
BMW 3 Series 318i SE 36.6p 55.8p
Ford Focus 1.6 Zetec 24.2p 41.7p
Rover 75 2.5 Connoisseur SE 40.5p 77.8p

  • All figures based on 30,000 miles/3 years ownership. Service cost excludes tyres, exhaust system and major mechanical replacements.