BMW Z4 (2009-2016) review - MPG, CO2 and Running Costs

No matter which version of the 2.0-litre four-cylinder turbocharged engine you chose, whether it’s the sDrive18i, 20i or 28i, BMW claimed average fuel economy figures of 41.5mpg and CO2 emissions of 159g/km across the board. These numbers were pretty good for a sports car, although the newer, more efficient Audi TT Roadster 2.0 TFSI had the BMW Z4 beaten, with figures of 47.1mpg and 140g/km.

Of course all the official figures are generated during a computer controlled test cycle, so if you use all the Z4’s performance potential on the road then fuel consumption and emissions have the potential to rise considerably. The larger capacity engines, driven hard, are likely to consume more.

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It’s worth noting too, that opting for the eight-speed automatic gearbox on the Z4 had no impact on the numbers. Unlike Audi with its TT, BMW didn't offer a diesel version of the Z4, so don’t go looking for a super-frugal option.

The range-topping sDrive35iS with its six cylinder engine will naturally be much more expensive to run than the four cylinder cars, as it can only manage to return 31mpg and emits 211g/km of CO2. Newer rivals like the SLK 55 AMG and Boxster S PDK both do better in this area, with emissions of 195g/km and 188g/km respectively – making the BMW marginally more expensive to tax, and increasing its Benefit-In-Kind rating a touch for company drivers.

Insurance groups

Insurance premiums are going to be pretty hefty whichever model you choose, with the Z4 range falling into groups 38 to 43 depending on performance. On a ‘like for like’ performance basis, the Mercedes SLK and Porsche Boxster are each a little more expensive though.

Depreciation

The Z4 also benefits from strong residuals, with our experts predicting that most versions of BMW’s roadster will retain around 50 per cent of their new value after three years. This is around the same level of return you might expect from a Mercedes SLK or Audi TT, but invest in a Porsche Boxster and your money should do better.