Reliability is a major consideration when buying a new car - which is why the What Car? Driver Power Survey is such a help. The publication’s most recent poll collected data from 14,000 car owners across the country, asking them about the faults they have experienced over the last 12 months.

The survey revealed that a third of drivers encountered at least one fault over the last year.

The poll penalised cars that suffered mechanical issues by subtracting points and awarded points to those vehicles that had fewer problems.

What Car? looked at the following areas: battery, bodywork, brakes, engine, engine electrics, exhaust, exterior lights, fuel system, gearbox/clutch, interior trim, non-engine electrics, steering suspension and ‘other’.

Here are the top 10 most unreliable cars in the UK, according to What Car?

  1. Mercedes-Benz B-Class - Score: 46.2 per cent

A third of B-Class buyers encountered issues that meant their cars could not be driven - and took more than a week to sort out. Most complaints surrounded the engine, engine electrics and gearbox/clutch.

  1. Mercedes-Benz E-Class - Score: 46.1 per cent

Interior and electrical issues topped E-Class problems. 24 per cent of owners had to deal with a mechanical issue of some kind.


  1. Nissan Qashqai diesel - Score: 44.2 per cent

49 per cent of diesel Qashqai owners had to take their car to the garage, with non-engine electrical systems topping the list. 20 per cent encountered battery failures.

  1. Land Rover Discovery Sport diesel - Score: 43.8 per cent

40 per cent of owners reported issues, predominantly with interior trim and bodywork. Engine and non-engine electrics also appeared on the fault list.


  1. Jeep Renegade - Score: 42.1 per cent

43 per cent of Renegade owners said they had a fault, with the engine, engine electrics and brakes causing most issues. The rugged off-road marketing didn't quite match the reality of this US 4x4.


  1. Jaguar XE - Score: 36.7 per cent

It looks great, but in terms of reliability, only the Jaguar garages have won out. Most issues were non-engine electrical related, but bodywork, engine, fuel system, steering and suspension all had faults. 44 per cent of owners experienced issues.


  1. Fiat 500X - Score: 32.3 per cent

33 per cent of owners encountered faults with the 500X, mostly connected to the bodywork and the electrics.


  1. Nissan Qashqai petrol - Score: 28.9 per cent

Another Qashqai makes this dubious list. 56 per cent of owners had issues, with the extensive list of problems led by batteries, bodywork and non-engine electrics.


  1. Volvo XC90 - Score: 22.6 per cent

Most issues with the XC90 related to non-engine electrics and software systems, which often took more than one garage visit to resolve. However, all work came under Volvo's warranty.

  1. Range Rover Sport diesel - Score 14.5 per cent

It may be one of the most desirable diesel off-roaders on the planet, but the Range Rover Sport diesel falls down badly on reliability. A whopping two-thirds of owners experienced problems, mainly with the gearbox, drivetrain, engine and suspension - but a host of other issues also came up. Additionally, not all vehicle problems were addressed under the warranty.