Franchised dealers are losing service and repair work on cars still under the manufacturer's warranty to independent rivals, according to a survey by Bethell Fleet Services.

Four out of five of the 78 independent garages surveyed said that carmakers had rejected none or very few warranty claims, despite manufacturers' public claims that this would invalidate the warranty. Half the garages have had a successful warranty claim against a manufacturer in the past 12 months.

Tim Jones, Bethell Fleet Services commercial director, said: “This survey makes a nonsense of the claims of motor manufacturers and franchised dealers that failure to have a car serviced by those dealerships invalidates the manufacturer's warranty.”

Warranty work is a growing part of independents' businesses, with nearly half claiming it accounted for between 20-50% of their revenue.

Bethell also found that almost 85% of independents carried out work for contract hire companies, suggesting large fleets acknowledged this would not invalidate the manufacturer's warranty. Independents' labour rates can be up to two-thirds lower than those charged by franchised dealers.

“This survey has finally laid to rest the fallacy that franchised dealerships service and repair all vehicles still under the manufacturer's warranty while independents deal with cars which are outside that warranty,” said Mr Jones.

“Whatever they might say in public, most, if not all, motor manufacturers accept that the best independent garages, as long as recommended service intervals are observed and the correct parts used, can carry out work on cars still under warranty.”