Councils in England and Wales have been forced to pay out £22.8 million in compensation to drivers last year whose vehicles were damaged by potholes.
Which? magazine said local authorities in the north-west forked out the most at £8m.
The government allocated an extra £200m for local highway authorities in 2011 when it commissioned a Potholes Review, citing a "significant increase in the number of potholes on the already fragile local highway network."
But Which? found that the backlog of road repairs per local authority in England is getting bigger, growing from £53.2m in 2009 to £61.3m last year.
Local authorities have estimated that it would cost £12.93 billion to clear Britain's entire road maintenance backlog.