Which? Car has found that car dealers are not making it obvious how much interest customers will have to pay on their vehicle . The report, based on an investigation involving a number of undercover visits to showrooms, advises people thinking about buying a new car to avoid showroom finance deals, because of this lack of adequate but essential information about car finance agreements .

It found that the details of car finance deals were not properly explained and that, of the 15 dealerships involved, not one revealed the total cost of the interest on a car finance agreement. Such was the lack of information provided, Which? Have reported their findings to the Office of Fair Trading (OFT).

Two thirds of those asked also failed to mention the annual percentage rate (APR) for the deal, while a third did not even include it on their written quote. Without this knowledge, it is impossible to know how much interest you are liable to pay on a finance deal. Not stating the APR on a written quote also contravenes the Consumer Credit Act .

Peter Vicary-Smith, chief executive of Which? Said that When you take out a mortgage, the bank or building society has to clearly state APR rates up front, and explain terms and conditions fully. We think car finance deals should be conducted in the same way.