Exclusive: least reliable second-hand cars revealed

An analysis of thousands of warranty repairs* has revealed the previous-generation Range Rover is the least reliable second-hand car you can buy, with the luxury SUV getting an overall dependability score of just 20.2%.

The data, shared with carwow by aftermarket warranty firm Warrantywise, covers 200 models of car, each of which is given a reliability rating based on a number of factors, including actual warranty repair requests, plus factors such as vehicles’ ages and mileages.

All the cars included in the data are outside of manufacturer warranties and under 10 years old, while in order to give as level a playing field as possible, Warrantywise had to have at least 100 examples of each car on its books in order for it to be included in this run-down.

The previous-generation BMW M3 was the next least reliable car based on Warrantywise’s data, with the Range Rover Sport the third least reliable model.

This list of the 15 least reliable cars includes the average age of each car when a warranty repair was needed, the average cost of a fix and the most likely component to cause a warranty repair, as well as highlighting the most expensive repair paid out for each car, and the reason behind those repairs.

15. Tesla Model S (2012-22)

Reliability score 33.5%
Average age 4.9 years
Average repair £1,003
Most common fault Central locking
Most expensive repair £4,402

The Tesla Model S was a groundbreaking car, being the first luxury EV and popularising Tesla across the world, but it seems it could be more dependable as a second-hand prospect.

The most common fault is linked to its central locking system, and while the average warranty repair cost for a Model S was relatively low compared to some of the cars in this rundown, the average age of these Teslas when a repair was needed is relatively low.

14. Ford Ranger (2012-22)

Reliability score 33.4%
Average age 5.2 years
Average repair £1,246
Most common fault EGR valve
Most expensive repair £13,993

Pick-up trucks tend to have a tough life, but it seems the previous-generation Ford Ranger is relatively likely to need a fix over the course of its duties.

Exhaust gas recirculation valves – which help reduce emissions – were the most likely culprits for warranty repairs, and while the average cost of a warranty repair wasn’t too high for the Ranger, the almost £14,000 bill for an engine fix that was the highest warranty repair for a Ranger is somewhat eye-watering.

13. Audi A7 (2012-19)

Reliability score 33%
Average age 6.5 years
Average repair £2,431
Most common fault Injector
Most expensive repair £11,222 (gearbox)

The Audi A7 is a stylish and luxurious coupe-cum-hatchback, but while it’s a talented, appealing model, Warrantywise’s data indicates the previous-generation A7 could be more reliable.

Fuel injectors are the most common reason for a warranty repair being made, while the average costs for repairs overall was £2,431. One gearbox fault prompted a far higher bill, though, at a cool £11,222.

12. Mercedes S-Class (2012-19)

Reliability score 32.8%
Average age 6.9 years
Average repair £1,423
Most common fault NOx sensor
Most expensive repair £16,277 (engine)

Another luxurious car, the Mercedes S-Class is famed for being a showcase for the technologies and features lesser cars will have in years to come, but Warrantywise’s data shows some of the systems on the previous-generation S-Class can develop issues as the car ages.

Nitrogen oxide sensors are the most common reason for a repair being funded by Warrantywise, while one engine problem led to a bill of over £16,000.

11. Peugeot RCZ (2012-15)

Reliability score 32.2%
Average age 7.5 years
Average repair £1,040
Most common fault Turbo
Most expensive repair £6,593

The Peugeot RCZ is a stylish coupe that was only made for a few years, but that doesn’t stop it from putting in an appearance in Warrantywise’s least reliable rundown.

The most likely issue to cause a warranty repair for the RCZ is related to its turbocharger, but while the average bill for faults overall is a reasonably palatable £1,040, one Warrantywise customer had a repair that ran to well over £6,000.

10. BMW M5 (2012-19)

Reliability score 30.8%
Average age 6.8 years
Average repair £2,125
Most common fault Suspension
Most expensive repair £10,129 (timing chain)

A high-performance car like the BMW M5 (this data covers the previous F10 and current F90 models) tends to bring with it expectations of not inexpensive bills, but the owner who suffered a timing chain fault necessitating a repair of over £10,000 must have been glad they took out a warranty.

The most common fault for M5s on Warrantywise’s books, meanwhile, was linked to its suspension, while the average payout was a little over £2,000.

9. Mazda CX-5 (2012-22)

Reliability score 29.6%
Average age 5.8 years
Average repair £1,784
Most common fault Turbo
Most expensive repair £5,776 (engine)

This data covers both the previous and current CX-5, and it seems that while Mazdas and Japanese cars in general have a strong reputation for dependability, the CX-5s on Warrantywise’s books could perform better in this regard.

We’re looking at the previous and current generations of the CX-5 here. It’s interesting to note that Mazda’s petrol engines for the CX-5 are not turbocharged, making the diesels responsible for the most common fault on Warrantywise’s books.

8. Bentley Continental GT (2012-18)

Reliability score 29.1%
Average age 7.4 years
Average repair £2,237
Most common fault Electrical system
Most expensive repair £6,227 (turbo)

The previous-generation Bentley Continental covered here has started to drop to temptingly low prices on the second-hand market, but its presence as one of the less reliable cars Warrantywise has on its books might put those attractive used values into perspective.

After all, the rule of thumb is that if you couldn’t afford to run a car when it was new, you certainly can’t when it’s got a few years under its belt and miles on its clock.

7. Audi Q7 (2012-20)

Reliability score 25.7%
Average age 7.1 years
Average repair £1,345
Most common fault Electrical system
Most expensive repair £8,719

The first-generation and early models of the current Q7 covered by Warrantywise’s data seem to be relatively likely to require a repair, but the good news is that the average age of Q7s when a repair was required is relatively high in this company.

One camshaft fault did require a chunky repair bill, but the average cost of Q7 fix is a little more palatable, at £1,345, with electrical issues most likely to cause issues.

6. Porsche Cayenne (2012-18)

Reliability score 24.9%
Average age 6.7 years
Average repair £1,496
Most common faultElectrical
Most expensive repair £6,360

The previous-generation Porsche Cayenne to which this data refers is a hugely accomplished vehicle, but that doesn’t stop it from featuring in the top 10 least reliable cars according to Warrantywise’s data.

Electrical issues were again responsible for the largest number of warranty repairs, while one engine fault prompted a bill of over £6,000.

5. BMW X6 (2012-19)

Reliability score 23.6%
Average age 6.8 years
Average repair £2,079
Most common fault Suspension sensors
Most expensive repair £9,613 (Fuel system)

As with the Porsche Cayenne, the BMW X6 is another large luxurious SUV. We’re dealing with the previous-generation X6 and the model that came before that, with one fuel-system fault bringing about a chunky bill of a little under £10,000.

Prospective X6 owners looking on the used market would do well to check there are no knocks or clunks from its suspension, and check that dynamic dampers work properly, if fitted, due to the suspension sensors being the most likely reason for a warranty repair.

4. Porsche Panamera (2012-19)

Reliability score 23.4%
Average age 6.5 years
Average repair £1,617
Most common fault Electrical
Most expensive repair £10,785 (timing chain)

The second Porsche in Warrantywise’s top 15 least reliable cars, the Panamera covered by this data is the previous-generation model, and early versions of the current car.

One timing chain fault caused a warranty repair of over £10,000, while the most common source of complaint was the Panamera’s electrical system.

3. Range Rover Sport (2012-19)

Reliability score 23.1%
Average age 6.6 years
Average repair £1,767
Most common fault Suspension
Most expensive repair £22,358

If you thought the Panamera’s £10k-plus timing-chain bill was high, one Range Rover Sport owner had a warranty repair costing more than double that following an engine fault with their car.

Warrantywise’s data covers the first-generation Sport, plus older versions of the car that’s just been replaced, while as with the BMW X6, prospective owners of used Range Rover Sports should pay close attention to its suspension system.

2. BMW M3 (2012-19)

Reliability score 21.4%
Average age 7.4 years
Average repair £2,123
Most common fault Throttle body
Most expensive repair £12,115 (gearbox)

The BMW M3 seems to be less reliable than its larger M5 sibling, based on this data, which doesn’t apply to the current car but the previous F80 M3, and the earlier E90 model.

Throttle bodies seem prone to playing up in these cars, while one £12,115 bill for a transmission is one of the reasons why the M3 takes second place in this rundown.

1. Range Rover 2012-19

Reliability score 20.2%
Average age 7.2 years
Average repair £1,607
Most common fault Suspension
Most expensive repair £23,890 (electrical system)

The unenviable top spot of the least reliable car on Warrantywise’s books had to fall to one car, and it’s the previous-generation Range Rover. The average warranty repair cost isn’t as high as some of the cars on this list, but one electrical problem prompted serious work, and an even more serious bill, while the proportion of owners needing a warranty repair was also high.

As with the smaller Sport model, suspension was a relatively weak spot for the full-fat Range Rover.

*Disclaimer: average repair costs collated over a period between 2021 and 2022. Since the sample was selected, Warrantywise has seen a significant rise in the price of labour and parts, which will impact future repair costs.