Britain’s recent heat wave boosted the values of used cars with air conditioning, and made cars without the feature much harder for dealers and private owners to sell, according to Glass’s Information Services.

“Right across the market buyers are shunning cars that don’t allow them to escape the heat,” said Glass’s senior car editor Jeff Paterson.

“Although temperatures are now easing, dealers remain very cautious about adding cars without air conditioning to their stock. In addition, the premium for a family-sized hatchback or saloon with ‘air con’ before the heat wave was around £200, but that figure is now nearer to the £500 mark.

“There is definitely a trend that is seeing manufacturers add air con or climate control as standard kit on more of their cars; even small vehicles at the budget end of the market such as the Daewoo Matiz now include it.

“Such trends in the motor industry very rapidly become the norm, and I think we are beginning to see air con added to the list of most customers’ minimal requirements. As a result, the increased premium over non-air conditioned cars may well stay in place during the winter months.”