Motorists with nearly-new cars are at risk of having illegal insurance cover as some motor traders aren't transferring the registration for up to 90 days.
A BBC investigation found that some dealers hold onto the documents so they qualify for large discounts from car manufacturers, and that leaves some V5C log books without being updated for several months.
These pre-registered vehicles are excess stock that have been sold cheaply to the dealers by manufacturers.
Pre-registered cars must be kept off the road for 90 days before being re-sold and these delays can be even longer if they were registered as a business fleet vehicle.
The BBC Radio 4 'You & Yours' programme found that many online car brokers fail to divulge this information in the small print and some of the cars in question are being sold to customers before the end of that period. This means vehicles are still registered at the dealership while being driven by the customer.
One buyer, Andrew March told the show: "I couldn't drive the car because it had been declared off-road, and the car's log book had been withheld so I couldn't re-tax it."
"It's not really a problem that the industry takes seriously and it's really only word of mouth and education that can stop this."
Written by Jack Healy