Almost half of motorists reckon they have fallen victim to rogue car mechanics, a survey showed today.

They are costing the UK £8 billion in over-charged, unnecessary or poor-quality work, according to the poll by insurance.co.uk

As many as 34 per cent believe they have paid £100 more than they should have for car servicing, while 51 per cent estimate they have been over-charged £500.

A total of 12 per cent think their bills have been stretched by an additional £1,000, while three per cent put the figure as high as £3,000.

Asked specifically if they felt they had been conned by a mechanic, 48 per cent of the 1,376 car owners surveyed thought they had.

While nearly three in five drivers would always take their car to a garage for maintenance and servicing, 38 per cent would only take their car to a professional if it needed major maintenance work.

Five per cent said they never took their car to a garage, preferring to do the job themselves.

More than half (52 per cent) opt to stay away from professional mechanics for fear of being overcharged for repairs or servicing.

Forty-eight per cent believe a garage will try to do more work than is actually necessary and 34 per cent – and 42 per cent of women – fear their lack of knowledge about cars will be exploited.

In addition, 28 per cent questioned the quality of the work from a mechanic, garage or workshop.

Steve Grainger, head of insurance.co.uk, said: “While the vast majority of car mechanics and garages are entirely reputable, our research highlights that there are a number of rogue tradesmen trying to exploit drivers and consumer confidence in the industry is low.

“In the current economic climate car owners could be holding on to used cars for longer. For the safety of all road users, it’s vital we make sure our vehicles are adequately maintained and serviced.”