Reliability Survey: Most and least reliable diesel cars

Diesel cars may have fallen out of favour with the Government and the car buying public in general, but they are still a viable proposition for many drivers.

They can be the best option for high-mileage motorway motorists because they’re usually more economical on fuel than their petrol counterparts, generally go further on a tank of fuel and are quicker to refuel than pure electric models alternatives. 

A diesel model is also a good choice if you want a good tow car with plenty of oomph for pulling a caravan or trailer.  

However, many diesel models are less dependable than their alternatively fuelled siblings. In fact, along with pure electric models, diesels are the most problem-prone fuel type, with a joint-highest fault rate of 26%. Petrol cars are more robust, with a fault rate of 20%, while hybrids are best of all with just 17% of plug-in hybrids (PHEVs) and 18% of regular hybrids going wrong.

How the research was carried out

To compile the latest What Car? Reliability Survey we asked 21,732 car owners to give us the lowdown on how reliable their car had been over the previous 24 months. First we asked them to tell us if the car had suffered any problems, and, if so, how much each one had cost to put right and how long it had kept the car off the road.

The survey, conducted in association with MotorEasy, was compiled using this information. It contains data on 178 models aged up to five years old from 32 different car brands.

The 2024 What Car? Reliability Survey is live, tell us about your car now

Most reliable diesel cars 

1. Volvo XC40 (2017-present)

Reliability rating 99.3%

Just 9% of the diesel Volvo XC40 models in our survey had a glitch, compared with 22% of the petrol models. The only areas to cause headaches were the brakes and sat-nav/infotainment system. Volvo and its dealers dealt with any issues swiftly and for free. All cars were fixed under warranty and all were back out of the workshop in less than a week. 

2. Volvo XC60 (2017-present)

Reliability rating 96.2%

The larger Volvo XC60 is almost as robust as the XC40, but diesel XC60s are just behind petrol and hybrid versions because some took longer to fix when they went wrong. 

Diesel and petrol XC60s have a fault rate of 11%, and 14% of plug-in hybrids went wrong. Sixty-eight percent of petrol and hybrid models were repaired in a day or less, while 60% of diesels were put right in this time; 20% of diesel owners had to do without their cars for more than a week. On a positive note, all work was done for free. Brake and electrical problems were the main issues. 

3. Jaguar F-Pace (2016-present)

Reliability rating 95.4%

The Jaguar F-Pace is far less troublesome than some Jaguar models; according to owners only 15% of their cars had any issues. The air-con, battery, bodywork and non-engine electrics all gave cause for concern. Although 24% of cars were rendered undriveable by their faults and took more than a week to put right, Jaguar covered the cost of all remedial work.  

4. Audi Q7 (2015-present)

Reliability rating 95.2%

Just 11% of Audi Q7s we were told about had issues, with the engine being the only problem area. Half of the cars were still driveable and fixed within a day, while the other half were stuck in garages for up to a week. Thankfully, Audi covered the cost of 50% of the cars that suffered faults but the other half of owners were faced with repair bills of up to £750.

5. BMW X5 (2018-present)

Reliability rating 95% 

One in ten of the BMW X5s in our survey had a problem. The vast majority of problems were with the engine electrics and non-engine electrics. All of the cars were in garages for up to a week but luckily BMW covered the cost of all repairs. 

6. Mercedes GLC (2015-present)

Reliability rating 94.8%

Steering and non-engine electrical issues caused the most grief for the 18% of Mercedes GLC owners who told us their cars had gone wrong. All cars could still be driven, but 67% of them took up to a week to put right, while the remaining 33% took longer than a week. And all repairs were covered by Mercedes for free. 

7. Volkswagen Tiguan (2016-present)

Reliability rating 94%

Slow repairs bring the score of the Volkswagen Tiguan down: 44% of the cars we were told about in our survey were out of action for more than a week. Just 13% of owners reported issues with their family SUV, with problems occurring with the battery, brakes, exhaust, sat-nav/infotainment and steering. On a positive note, all cars were fixed by Volkswagen for free. 

8. Volkswagen Golf (2013-2020)

Reliability rating 93.5%

The previous-generation Volkswagen Golf is one of the most popular cars out there, and thankfully it’s quite a reliable one, too, with just 7% of survey respondents reporting an issue with their car. Half of these cars were driveable and fixed in one day to one week, while the remaining half were out of action for longer than a week. Volkswagen covered the cost of most of the repairs (67%), while the remaining 33% of Golf owners were faced with bills ranging from £101-£300. Bodywork and engine electrical issues were the only areas of concern. 

=10. BMW X3 (2018-present)

Reliability rating 93%

One in four BMW X3 owners in our survey reported a fault with their car, with the most problematic areas being the engine, sat-nav/infotainment, non-engine electrics, air con and engine electrics. The good news is that BMW covered the cost of all repairs and most cars were still driveable, with only 30% taking more than a week to repair. 

=10. Ford Focus (2018-present)

Reliability rating 93% 

Gearbox/clutch issues were the only problems reported of the 20% of Ford Focuses we were told about. Ford and its dealers dealt with any issues swiftly and for free. All cars were fixed under warranty and all were back out of the workshop in less than a week. 

Least reliable diesel cars

1. Ford Kuga (2013-2020) 

Reliability rating 76.1%

The previous-generation 2013-2020 Ford Kuga diesel is really starting to show its age; 28% of the cars reported on in our survey had an issue. The battery and various electrical systems, including the sat-nav/infotainment system were the main culprits. Only one in every five cars was fixed in a day or less, 52% took up to a week to put right and 28% were out of action for more than a week. Repairs were cheap though: Ford paid for 89% of repair work and the other faults were fixed for £50 or less. 

2. Skoda Karoq (2017-present)

Reliability rating 76.9%

Diesel Skoda Karoq models have a similar fault rate to their petrol counterparts: 22% compared with 23%, but their overall rating is far lower (76.9% versus 96.0%) because their faults were more serious and time-consuming to put right. Only 37% of diesel Karoqs were repaired within a day, while 64% of petrol were, and 31% of diesel models were out of action for more than seven days. The most common problems were with non-engine electrical systems.    

3. BMW 3 Series (2019-present)

Reliability rating 78.0%

Diesel versions of the BMW 3 Series went wrong more often than petrol models (they had a 30% fault rate compared with 11% for petrol), but they were pricier and slower to put right. Exhaust and sat-nav/infotainment issues were the most common complaints, rendering 33% of diesel models undriveable and out of action for more than a week. While all faulty petrol models were fixed under warranty, only 44% of diesel issues were. 

4. Range Rover Evoque (2011-2019)

Reliability rating 80.6%

Virtually all the previous-generation Range Rover Evoques reported on in our survey were diesel models, and their owners told us 27% of them had problems. Issues with the engine electrics were the most common complaint, followed by exhaust system faults. Although Land Rover fixed all issues for free, just over half of the faulty cars were out of action for more than a week and 19% couldn't be driven. 

5. Volkswagen Golf (2020-present)

Although diesel versions of the Volkswagen Golf suffered far fewer problems than petrol models (they had a 33% fault rate compared with 56% for petrol Golfs), they were pricier and slower to put right. Owners told us 100% of petrol models were fixed for free, while only 83% of diesels were, and some cars cost £1000-£1500 to put right. On top of that, 50% of diesels were off the road for more than a week compared with 42% of petrol Golfs. 

6. Nissan Qashqai (2014-2021)

Reliability rating 83.2%

Diesel versions of the previous-generation Nissan Qashqai are proving far less durable than their petrol counterparts: 50% of them had issues, compared with 13% of petrols. Various electrical systems and the brakes were the biggest headaches for diesel Qashqai owners, who told us a third of faulty cars took more than a week to fix. The only saving grace is that Nissan covered the cost of all remedial work. 

7. Skoda Superb (2015-2024)

Reliability rating 84.1%

A petrol 2015-2024 Skoda Superb is a better bet than a diesel if you're after a dependable car because only 18% of petrols suffered a glitch, compared with 33% of diesels. The engine and suspension were the most frequently cited bugbears. The good news is that 40% of cars were fixed in a day or less and no owners were charged anything for repairs. 

8. BMW 5 Series (2017-2023)

Reliability rating 85.6%

Thirty-one percent of the 2017-2023 BMW 5 Series models reported on in our survey went wrong, with around two-thirds of them affected by electrical issues. On a positive note, all faulty cars remained driveable and 44% were put right in a day or less; only 22% sat in the garage for more than a week. BMW covered the cost of all repairs, too. 

9. Range Rover Velar (2018-present)

Reliability rating 88.1%

Range Rover Velar owners complained that 32% of their cars had issues, many with the 12-volt battery. Although all cars could still be driven, it took Land Rover and its dealers more than seven days to fix 63% of them. While the car maker paid for 67% of repairs, some owners paid up to £50 and others more than £1500 to get their cars put right. 

10. Land Rover Discovery (2017-present)

Reliability rating 88.3%

Engine problems were the main gripe of the 32% of Land Rover Discovery owners who told us their cars had gone wrong. There were also some reports of issues with the air-con, battery, bodywork, interior trim and sat-nav/infotainment system. Sixty percent of cars were in the workshop for more than a week, but the silver lining is that Land Rover paid for all faulty cars to be fixed. 

To read the reliability data for other car classes follow these links:

All cars and SUVs here
Most reliable small cars
Most reliable family cars
Most reliable executive cars
Most reliable luxury cars
Most reliable small SUVs
Most reliable family SUVs
Most reliable large SUVs
Most reliable seven-seaters
Most reliable electric cars
Most reliable electric SUVs
Most reliable sports cars
Most reliable car brands

Reliability of diesel cars aged up to five years old

About the report author

Claire Evans has been a motoring journalist for more than 30 years, working on consumer issues for a great deal of that time. After a stint as the advice columnist for Carweek magazine in the 1990s, she also spent six years working on motoring content for Which?. It is here she oversaw the running of the charity's annual used car reliability survey.

Claire launched the What Car? Reliability Survey in 2017, and since then has helped thousands of buyers choose the most reliable new cars and SUVs, as well as the most dependable used cars.

For all the latest reviews, advice and new car deals, sign up to the What Car? newsletter here

Read more: The most and least reliable cars in every class >>