BMW Z4 review: sports car, luxury cruiser or mini-GT? - MPG and running costs

Given the performance on offer, the Z4’s fuel economy isn’t too bad, with the 20i and 30i being the more economical models. The 20i returns 38.7 to 39.8mpg while, despite the additional performance on offer, the 30i will return 37.7 to 38.7mpg.

Unsurprisingly, the M40i is considerably thirstier with an official combined figure of 33.2mpg. Obviously, with all these figures, if you indulge in using the performance they’ll drop significantly. And given the size of the Z4’s fuel tank – a rather measly 52 litres – you could find yourself stopping for top-ups more regularly than you might like. 

Insurance groups are relatively low for the Z4 – the 20i is in group 30 or 31, the 30i in 33 or 34, while the M40i is in group 37. By way of comparison, a 718 Boxster is in group 44 and the Boxster S in group 47. 

There’s a three-year warranty and a servicing package on offer, but running a Z4 shouldn’t break the bank as with extended condition-based servicing the Z4 shouldn’t need all that much in the way of attention from BMW dealers, especially as roadsters typically cover lower than average mileages.