Car makers are introducing the move in a bid to improve fuel economy, increase space and reduce production costs.
But CAP editor John Watts warned this week the policy was a mistake that could cost them dearly in the long-term by pushing up vehicle running costs.
He said: 'I do not see how this could fail to damage residual values and those manufacturers who do proceed with these plans may well find their product penalised heavily on the used car market. This in turn could impact on the model choices fleets make because they always need to maximise their future returns.
'The security and peace of mind offered by carrying a spare wheel is not something most people will be willing to give up. The prospect of missed deliveries, drivers stranded miles from home and increased costs for operators is likely to influence vehicle choice in both the new and used markets.'
An increasing number of manufacturers do not supply a spare tyre. In some cases, this is because a car is using liquefied petroleum gas, with an extra fuel tank stored where the spare wheel would be.
However, some others are dropping the spare wheel because they feel customers prefer extra space to the security of a spare tyre. Faced with a puncture, there is a choice – rely on a temporary puncture repair kit to fix the damage, continuing the journey at no more than 50 mph and for a limited mileage, or call for help and wait for a replacement.
Watts said: 'Even circumventing the problem by fitting such cars with run-flat-capable tyres will simply add to the costs of a vehicle and again cause concern to potential buyers in the used car market.
'All of these factors strongly suggest that manufacturers think again before going ahead with a plan which seems to fly in the face of common sense.'