The barometer here is twofold: how do the latest Cayman’s running costs stack up against the previous one’s, and how does it compare with its rivals.

That’s a gauge for any car, of course, but doubly pertinent for a sports coupé that has been separated from two of its cylinders.

Nic Cackett

Nic Cackett

Road tester
Porsche enjoys some of the industry’s best residuals and despite the contentious engine – the Cayman is no different

Buy the standard Cayman and fit it with the PDK gearbox and Porsche claims you will see 40.9mpg combined and 158g/km CO2. That’s 5mpg and 25g/km more efficient than the car it replaces and a similar amount clear of BMW’s M2.

However, buy the car with a manual gearbox and the larger engine and the advantage narrows. At 34.9mpg, the S’s official average is only 3.5mpg ahead of the old 3.4-litre GTS’s.

At MIRA last year, the even more powerful GT4 returned 9.4mpg during track use; 10.3mpg from the new S shows just how immoderately thirsty a turbo engine can still be.

During TrueMPG testing, the 718 averaged 28.4mpg, which isn’t awful but neither is it a cast-iron economic reason for preferring the car to a nearly new example of its larger-capacity predecessor. Our test car’s 54g/km reduction in CO2 emissions over the GT4 encapsulates the incentive to Porsche as an organisation. But the £270-a-year reduction in road duty it represents hardly seems persuasive recompense for a repeat buyer.

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If you are keen on getting a 718 Cayman we would advise sticking with adaptive Sports suspension (£1133) and locking rear diff with PTV (£890), and avoiding the biggest optional rims. However, we haven’t tried the standard Cayman in the UK so don’t yet know if the S is worth its premium. 

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