Best and worst older cars for reliability: sports cars and coupes

How dependable are cars as they get older? Here’s what the owners of sports cars and coupes between six and 15 years of age have told us...

Audi TT

Most reliable Audi TT (2006-2014)

Reliability rating 93.2%

What went wrong? Battery 4% Brakes 4% Engine electrics 4% Non-engine electrics 4% 

Although 18% of TTs had a fault, the areas affected weren’t the most serious; the battery, brakes, engine and non-engine electrics each accounted for 4% of problems. Most of the cars could still be driven and were fixed in a week or less; no repair bills exceeded £500. 

Owner comment: “It has fantastic build quality and reliability; I haven’t had a single problem with it”

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Mazda MX-5 (2005-2015)

Reliability rating 93.0%

Compared with the Audi TT, slightly fewer (14%) MX-5s went wrong, but issues were split evenly across seven areas: air-con, bodywork, brakes, exhaust, gearbox, non-engine electrics and suspension. All of the cars could still be driven and a small percentage were fixed under warranty; more than half cost less than £200 to repair and only a small number cost up to £1500.

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BMW 6 Series Coupé/Convertible (2003-2011)

Reliability rating 92.7%

Owners reported that 25% of 6 Series cars had a problem, with issues centring on brakes and non-engine electrics. All of the cars were driveable and back on the road in less than a week; most costs were less than £50, but a few were up to £300. 

Least reliable BMW 3 Series Coupe / Convertible (2006-2013)

Reliability rating 57.0%

What went wrong? Brakes 11% Suspension 11% Engine 6% Exhaust 6% Gearbox 6% Non-engine electrics 6%

BMW 3 Series Convertible (05 - 14)


The 3 Series gets the wooden spoon for reliability, with 53% of cars suffering a fault, 17% of them to do with the engine. Other problem areas included the suspension, air-con, brakes and fuel system. Most cars were driveable and were repaired in less than a week; while some cars were fixed under warranty, others cost more than £1500 to put right. 

Owner comment: “I was shocked by the high price I had to pay for what I consider to be faulty parts” 

BMW Z4 (2003-2009)

Reliability rating 65.8%

The older Z4 isn’t as dependable as its newer sibling; 54% of cars went wrong, with suspension issues being by far the most common complaint. There were also reports of engine and exhaust system faults. Most cars were fixed in less than a day, and while most repair bills didn’t exceed £500, some were more than £1500.

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Mercedes-Benz SLK (2011-2016)

Reliability rating 74.9%

The SLK wasn’t plagued by lots of problems; 26% of cars had a fault, with brakes and suspension the most commonly cited areas of concern, followed by the engine and gearbox. It lost marks for reliability because more than half of cars languished in the garage for more than a week; most of them cost up to £500 to fix and a small percentage were more than £1500.