German cars, once famed for their reliability, have been given the thumbs down in a new Which? magazine survey, according to a BBC report which said that leading brands such as Volkswagen and Mercedes-Benz all fared worse in the magazine's annual reliability survey than in recent times.

Which? is published by the UK's Consumer Association and its views are well respected.

The BBC said less prestigious brands such as Ford performed better than in the past, overtaking their German rivals, and overall, Japanese cars were found to be the most reliable in the survey of 80,000 readers, comparing 138 different models.

The BBC said that Mercedes-Benz slipped two categories, from best to average, in reliability, according to the survey, and added that a Which? magazine spokesman said: "No major German marque has escaped the steady decline we have noticed in recent years."

The BBC said BMW trod water in the survey, achieving a disappointing average reliability rating for the fourth consecutive year, but Which? readers expressed greater dissatisfaction with Volkswagen cars.

The BBC said the maker of such leading models as the Golf and Polo, was downgraded by Which? readers to the poor reliability category.

Two other Volkswagen-owned companies, Seat and Audi, dropped from good to average in the reliability tables, the BBC report said, while the sporty Audi TT received one of the magazine's lowest scores for reliability for years.

Overall, no German carmaker managed to make it into either the best or good categories, the BBC noted.

"German cars were once known for their solid build-quality and dependability, but it seems no major German marque has escaped the steady decline we have noticed in recent years," a Which? magazine spokesperson told the BBC.

There was better news for US giant Ford, which the survey found has raised its game in recent times, the report said, adding that, consistently rated poor in the survey from 1998 to 2000, Ford has managed to clamber into the good category, having been rated average last year.

According to the report, Which? said the most reliable cars wre Honda's Accord and Jazz [Fit], the Mazda 323, Nissan X-Trail SUV and Toyota Celica.

Dominating the top reliability places for both manufacturers and individual car models were the Japanese and other Asian makers, with Honda, Hyundai, Lexus, Mazda, Nissan and Toyota all in the best category of maker-reliability, the BBC said.