In an analysis of recent sales of luxury marques, fleet marketing specialist Cars Direct has identified air con as the most important residual values factor on models such as BMWs, Mercedes-Benz and Jaguars. Fleets also need to insist that the specification list includes automatic transmission, manufacturer-fitted sunroof, specified alloy wheels and metallic paint. Leather upholstery and CD players are regarded as 'nice to have' but not essential, according to Cars Direct managing director Roger Woodward.

He said: 'Items previously considered as optionals now need to be specified as essential if companies are to maximise residual values on prestige vehicles. Cars with air conditioning consistently sell well in excess of CAP clean.'