For the latest car deals, sign up to the Which? Car email
Turbocharging helps cars perform better and use less fuel. But it may also reduce reliability.
This is according to the latest research by Warranty Direct. The company, which specialises in aftermarket vehicle warranties, keeps records of all claims made on its policies, and has been totting up turbo expenses.
What turbocharging does
Turbocharging works by forcing extra air into the engine, helping it breathe better, which in turn creates more power and uses fuel more efficiently. This can deliver a fuel economy improvement of up to 40% in diesel engines, and 20% improved fuel economy in petrol engines – both come with an accompanying reduction in CO2 emissions. So far so good.
Unfortunately, a turbo also increases the mechanical complexity of an engine, while placing extra stress on other engine and vehicle components. And this appears to be having a negative impact on vehicle reliability.
Double the failure rate
Warranty Direct has found that among its policy holders the average incidence rate for engine failure is 11.3%- but with turbocharged engines the failure rate is 27.8%. That’s more than double.
The cost of engine failure repair also increases, from an average £619 overall to £875 for turbocharged cars. The highest repair figure recorded by Warranty Direct for a turbo car is £2,485.
Turbodiesels suffer more breakdowns
Among diesel engines the average overall rate of problems on non-turbo cars is 25% at an average cost of £379, while for turbo cars the average problem rate is 32%, with an average cost of £399.
That said, the overwhelming majority of diesel engines are now turbocharged, so it’s not surprising to see more turbodiesel failures than non-turbodiesel ones; 85% of all the turbo failures handled by Warranty Direct related to diesel engines.
However, while non-turbo petrol cars still considerably outnumber turbo petrol cars, the average incidence rate is still higher for turbos – 37% versus 25%. And the average repair costs are also higher: £371 for turbo petrols, £335 for non-turbo petrols.
A growing problem?
The number of turbocharged cars on our roads looks set to increase because of the environmental and performance benefits they offer. Currently 50% of all cars built in Europe are turbocharged, but this figure could be as high as 85% by 2020, according to some industry experts. And the Warranty Direct data seems to suggest that there could be an increase in expense for the average motorist.
Follow Which? Car on Twitter
The Which? Car team is on Twitter, to offer you help and advice as and when you need it.
We’re monitoring our Twitter account every day, so if you have an account, please send us you thoughts and questions to @whichcar.
Don’t worry if you haven’t got a Twitter account – you can still stay in the loop by regularly checking www.twitter.com/whichcar.