According to new research involving nearly 500,000 vehicles, British motorists are more than twice as likely to suffer damage to their cars than their American counterparts because of poorly maintained roads.

The connection between damage and potholed roads could be a key factor in up to a third of all mechanical failures in the UK – costing more than £2.8bn a year in repairs – said Warranty Direct, which carried out the survey.

However, across the Atlantic, the comparable rate of failure falls to one in eight for the same vehicles.

For example, suspension related problems account for 42% of faults sustained by Ford Focus cars driven on British roads. This falls to 17% in the US.

A lack of spending on maintenance is to blame says Duncan McClure Fisher of Warranty Direct.

He said that although the UK’s Department for Transport spent an average of £10,000 per mile on roads in 2006, the US treasury spent one-and-a-half times more.

“Continuous driving over cracked or uneven road surfaces, or one sudden jolt from a pothole, can cause substantial damage to shock absorbers, springs, upper and lower arms and stabiliser bars,” he said.

“Even though the UK has just 250,000 miles of road compared to America’s four million, we are still a poor relation when it comes to road maintenance budget – and we’re paying for it in repair bills.”

However, the Highways Agency, which is responsible for motorways and A roads – the busiest roads in the country – said that road maintenance levels are at an all-time high. "Data from machine-based surveys of the surface of these roads show them to be in very good condition,” said an agency spokeswoman.

Warranty Direct analysed the relevant failures on nearly half a million vehicles across a sample of 25 vehicle manufacturers.

On average, 30.5% of cars will incur steering, axle or suspension damage that has deteriorated as a result, it says, of the UK’s poorly maintained roads.

On average, bills hit £285.39 for suspension repairs last year, although one was as £950.84.

Last year, the firm launched campaign website www.potholes.co.uk to campaign for an increase in funding for the estimated £1bn gap in road maintenance.