9:09 am, June 18, 2025
As temperatures continue to ramp up for the summer, car dealers across the country will be hoping to make some tidy profits on the sale of convertibles.
The romantic idea of ‘wind in the hair’ motoring, is one that appeals to a huge number of motorists but unfortunately, soft top sports cars can come with more than their fair share of reliability issues.
To help dealers know which cabriolets they should be stocking, Warranty Solutions Group (WSG) has been crunching the data to find which models offer the fewest headaches.
Based on a sample of 3,000 extended warranty claims paid by the firm between July 2024 and June 2025, the included soft top models with over 100 warranty sales across WSG’s dealer network.
The group then worked out many policies it sold for each used model against how many claims were made, to come up with an overall claim rate.
The lower the rate, the more reliable a convertible was throughout the year.
Perhaps unsurprisingly, the ever dependable and much-loved Mazda MX-5 topped the list with a claim rate of just 7.69%.
WSG’s experts say that the model is ‘refreshingly uncomplicated’ and described it as a ‘textbook case of less is more’.
The impressive result placed the MX-5 just ahead of BMW’s Z Series, which had a claim rate of 9.2% throughout the year.
Analysts said that while earlier Z3 and Z4 models had mixed reliability records, BMW has now ‘clearly addressed concerns in recent iterations’.
Other high performers included the Porsche Boxter (11.67%), Mini Cooper (12.72%) and Audi TT (14.01%).
At the other end of the scale, the Bentley Continental (24.07%) and Ford Mustang (25.71%) both struggled but it was the ‘style over substance’ Mercedes E-Class which came bottom with a score of 27.97%.
Meanwhile, the Continental was also model with the most expensive average claim at an eye-watering £2,432.65.
Most reliable convertibles
- Mazda MX-5 – Claim rate: 7.69%, Average claim: £456.46
- BMW Z Series – Claim rate: 9.20%, Average claim: £751.02
- Porsche Boxster – Claim rate: 11.67%, Average claim: £446.52
- Mini Cooper – Claim rate: 12.72%, Average claim: £535.36
- Audi TT – Claim rate: 14.01%, Average claim: £505.35
- Audi R8 – Claim rate: 14.29%, Average claim: £1,803.32
- Fiat 500 – Claim rate: 14.30%, Average claim: £473.75
- BMW 8 Series – Claim rate: 15.00%, Average claim: £1,447.73
- BMW 4 Series – Claim rate: 15.09%, Average claim: £869.41
- Mercedes SL – Claim rate: 18.00%, Average claim: £1,394.22
- Jaguar F-Type – Claim rate: 20.20%, Average claim: £517.23
- Porsche 911 – Claim rate: 20.57%, Average claim: £1,371.32
- Bentley Continental – Claim rate: 24.07%, Average claim: £2,432.65
- Ford Mustang – Claim rate: 25.71%, Average claim: £918.64
- Mercedes E-Class – Claim rate: 27.97%, Average claim: £678.91
Source: Warranty Solutions Group
Reflecting on the results, Martin Binnee, operations director of WSG, said: ‘Our data reveals a clear trend: modern convertibles no longer force drivers to choose between style and dependability.
‘Brands like Mazda, BMW, and Porsche have successfully delivered vehicles that combine driving enjoyment with mechanical trustworthiness.
‘As convertible ownership continues to grow in the UK, this ranking offers a valuable guide for both dealers and consumers – highlighting models that won’t just turn heads, but also go the distance.’
He added: ‘Historically, the Achilles heel of convertibles has been their susceptibility to faults such as Nox sensor failures, battery drain, and thermostat issues, symptomatic of the wider challenges around electronics integration and environmental exposure.
‘Electrical faults, in particular, have emerged as a persistent pain point for owners.
‘Yet the tide is turning. Brands like Mini, BMW, and Audi have made significant strides, closing the reliability gap with enhanced quality control, better system integration, and platform maturity.
‘Even Mercedes-Benz is regaining ground, although some models still carry legacy concerns. Meanwhile, manufacturers like MG and Alfa Romeo continue to struggle, highlighting the gap between design ambition and day-to-day dependability.
‘Ultimately, consumers are demanding more than just style – they want confidence. And in today’s market, reliability is fast becoming a key pillar of brand trust and long-term value.’
