German cars, once famed for their reliability, have been given the thumbs down in a survey by Which? magazine.
Leading brands such as Volkswagen and Mercedes-Benz all fared worse in the magazine's annual reliability survey than in recent times.
Less prestigious marques including the US' Ford performed better than in the past, overtaking their German rivals.
Overall, Japanese cars were found to be the most reliable in the survey of 80,000 readers, comparing 138 different models.
Mercedes-Benz slipped two categories, from best to average, in reliability, according to the survey.
BMW trod water in the survey, achieving a disappointing average reliability rating for the fourth consecutive year.
However, Which? readers expressed greater dissatisfaction with Volkswagen cars.
The carmaker, which manufactures leading models such 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, 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.
"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 said.
There was better news for US giant Ford, which the survey found has raised its game in recent times.
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.
Most reliable cars
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 for maker-reliability.