German cars are not as reliable as many people believe, according to a survey by aftermarket warranty provider Warranty Direct.

Audi, Volkswagen and BMW, including its subsidiary Mini, all performed poorly for engine failures in the past year, with Japanese engines proving by far the most reliable.

The only engines to have failed more often than Audi's in the past year were those from the now defunct MG Rover group, while Mini finished third from bottom. BMW and Volkswagen featured seventh- and ninth-worst respectively in the powerplant scale of shame.

At the top end of the table Japan took the plaudits as Honda and Toyota proved to be the manufacturers with the most reliable power units, while Mercedes upheld some German honour by taking third place.

Warranty Direct sampled 50,000 live policies to reach the conclusions, which revealed that one in 13 MG Rover engines had big problems while just one in 345 Honda engines had a serious issue. The engine failure rates therefore range from 7.88% to 0.29%.

The study also highlighted the cost of engine failures. An engine failure on a Range Rover Vogue recently led to Warranty Direct's highest claim - £12,998.46 - while one dealer quoted £14,853.60 to repair an engine on a Range Rover Sport after it failed catastrophically.

Warranty Direct Managing Director Duncan McClure Fisher commented: "Engine failures are the biggest fear for any motorist as they're the ones that can lead to the most astronomical costs because of the parts and hours or labour required to fix them.

"The number of failures may be low compared to areas such as axle and suspension damage but engine repairs almost always result in costs reaching the thousands for motorists who aren't covered by a warranty."