Increasing difficulties in the economy are making it harder for car buyers to organise their finances and make a purchase.
Along with the rise in fuel prices, credit is becoming increasingly difficult to obtain and it is subsequently affecting the market.
An alarming 30 per cent of cars checked by HPI are subject to outstanding financing agreements creating problems for both sellers and buyers when deals go wrong.
Nick Lindsay, director of HPI, said: "A vehicle on hire purchase or a lease agreement still technically belongs to the lender, and if that loan remains unpaid when an unwary consumer buys the car from the person who took out the loan, the lender has every right to take ownership of it."
This means that both buyers and sellers should be careful to make sure the car in question is fully paid for to prevent them being out of pocket when the lender comes to claim the vehicle.
Experian has also forecast changes in the car market as the credit crunch gets worse.
As consumers become more careful with their money Experian expects them to become more wary about making an expensive purchase as well as being careful about the car’s history.
Kirk Fletcher, managing director of the firm’s automotive division, believes financial concerns were already affecting used car sales.
"More and more consumers have been delaying their car purchase decisions," he said.
"The challenge for dealers is to watch the trends, identify areas of growth and recognise what motivates different kinds of customers," he added.