The vast majority of new cars, and many second-hand ones, are bought with finance agreements.
About two million are sold this way each year, with customers paying an initial deposit, then a monthly fee with interest for the vehicle.
In a complicated, and long-running, series of developments, many of these agreements have come under scrutiny.
In 2021, the FCA banned deals in which the dealer received a commission from the lender, based on the interest rate charged to the customer. It said this provided an incentive for a buyer to be charged a higher than necessary interest rate.
Since January, it has been considering whether compensation should be paid to people with these deals before 2021.
That has created the prospect of banks and other lenders having to make payouts totalling millions of pounds.
Last month, a decision at the Court of Appeal broadened the net of those who could receive compensation, potentially increasing the lenders’ final bill to billions of pounds.