For lots of us, buying a used car can be a huge gamble; a giant leap into the unknown with regards to reliability. But it doesn’t have to be like this. Sure, there will always be exceptions to the rule, but by analysis of even the most basic of reliability data, you can get a pretty good idea of what you’re in for and how likely it is the second hand motor you’re shelling out for will let you down in the long run. We’ve compiled a list based on the Warranty Direct Reliability Index featuring the models to avoid when making a purchase. Some of these might come as a surprise.

In reverse order, we kick off with…


  1. BMW 7 Series (2008 – 2015)


The current BMW 7 is a technological marvel, but if the previous edition – discontinued in 2015 – is anything to go by, there could be issues regarding its long term reliability. The previous 7 Series had an average repair cost of £614.48.

  1. Mercedes-Benz S- Class (1999 – 2006)


There are two Mercedes-Benz S-Class editions on this list and this is the marginally more reliable of the two. The key thing to keep an eye on with this edition, built between 1999 and 2006 are electrical problems and suspension issues.

  1. Skoda Superb (2002 – 2008)


This is a surprise this one, Skodas, these days are synonymous with reliability. The original Superbs however were largely used for private hire duties and are most likely to suffer from engine issues.

  1. BMW M3 (2007 – 2013)


There isn’t a single issue that sticks out when looking at the BMW M3, this suggests that the reliability issues are most likely down to the fact that these cars will have been driven hard. Average repairs cost £635.26.

  1. Mercedes-Benz M-Class (1998 – 2006)


The Mercedes-Benz M-Class makes its second appearance on this list. This time round however, it’s the original edition that debuted in 1998. This has always been a model to approach with a certain degree of trepidation, the survey suggesting that the suspension is the area to keep an eye on.

  1. Audi Q7 (2006 – 2015)


Into the top five we go, and the next quintet of vehicles are the ones you should regard with the greatest levels of caution when considering a purchase – or at least bring a mechanic along for the test drive. The Audi Q7 is a large SUV with equally big repair bills. Should it fail, you’re looking at repair bills of around £733.50.

  1. Mercedes-Benz R-Class (2006 – 2012)


Perhaps the ugliest of the recent Mercs, the R-Class has a reputation for reliability that prompts the question: Do you really want to buy a Mercedes-Benz R-Class?

  1. Bentley Continental GT (2003 – 2012)


The final three: the least reliable cars in the United Kingdom. For those who own a Bentley Continental GT, the cost of repairs isn’t likely to be an issue. The £603.49 average repair bills is most likely to feature suspension and electrical problems.

  1. Mercedes-Benz GL (2006 – 2012)


With a spectacularly low reliability index score of 533, buyers of the Mercedes-Benz GL-Class would be advised to be on their guard before committing to a purchase. All facets of this supersized SUV are big, the repairs bills in particularly, racking up an average cost of £563.90.

  1. Nissan GT-R (2009 – 2016)


Here it is. Officially the UK’s most unreliable car, according to the survey data. But is that title completely merited? Look at the actual data and the GT-R has a flawless record for air-conditioning, cooling, fuel system and transmission. The numbers for engine, electrics and gearbox are no worse than the other cars on the list, including the 40 cars that fell outside of the top-ten. The reason for the Nissan GT-R’s place on this list of shame simply comes down to the average cost of repairs, which clocks in at a whopping £3,516.01. To compound this, the average mileage of the vehicles surveyed came in on average at a paltry 21,690.

Source: Reliability Index

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