In Germany, the annual roadworthiness inspection known as the Hauptuntersuchung (HU) is a crucial process for all vehicle owners. Conducted by the country’s primary technical inspection organization, TUV, this extensive check evaluates millions of cars to determine which are safe to drive and which require immediate repairs.
The recently published 2026 TUV-Report analyzed 9.5 million inspections performed between July 2024 and June 2025, revealing a concerning trend: vehicle quality is declining. Overall, 21.5 percent of all vehicles—more than one in five—failed their annual inspection due to significant or dangerous defects.
While reliability issues affect cars across all categories and ages, particular attention this year was focused on electric vehicles, especially one manufacturer. For the third consecutive year, Tesla models ranked lowest in reliability, experiencing the highest failure rates.
The Tesla Model 3, specifically vehicles aged two to three years, recorded a defect rate of 13.1 percent, meaning one in every 7.6 cars did not pass the inspection on the first attempt.
The Model Y performed even worse, with a 17.3 percent defect rate in the same age group, marking it as the worst-ranked vehicle TUV has encountered in this category over the past decade. Inspectors most commonly found faults related to the axle assembly, suspension, brakes, and lighting systems.
However, the reliability issues are not inherent to all electric vehicles. In the critical two-to-three-year-old category, the electric Mini Cooper SE proved far more reliable with a marginal defect rate of just 3.5 percent. Additionally, the Fiat 500e led the small car segment among nearly new vehicles, demonstrating that electric cars can offer strong dependability without major maintenance concerns.
Minor defects also rose overall, now affecting 12.3 percent of cars, indicating that more owners are facing increased mechanical problems compared to previous years.
For older vehicles, typically held for 10 years or more, TUV introduced a new Long-Term Quality award recognizing brands with the lowest average defect rates for safety-related faults in this age group. Mercedes-Benz claimed the top spot, with an 18.5 percent defect rate for its oldest cars.
Audi followed closely with 19.2 percent, while Toyota secured third place at 22 percent. Notably, the defect rate for Mercedes vehicles over a decade old is roughly equivalent to the rate seen in two-to-three-year-old Tesla Model Y cars.
Though electric vehicles were the focus at the lower end of the rankings, traditional gasoline and diesel models also demonstrated reliability challenges. Poor performers in older categories included BMW’s 5-series and 6-series (in the four-to-five and eight-to-nine-year-old groups), the Dacia Duster (six-to-seven and ten-to-eleven years), and the Renault Clio (12 to 13 years old).
The 2026 TUV-Report serves as a clear reminder to both prospective buyers and current owners: regardless of whether your vehicle runs on combustion or electric power, the quality of its components and the maintenance it receives remain more critical than ever.
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