In-depth reviews

BMW X6 review - MPG, CO2 and running costs

Diesels offer expected economy, but running costs for the X6 are relatively high, particularly for company users.

Overall Auto Express Rating

4.0 out of 5

MPG, CO2 and running costs Rating

3.6 out of 5

£59,070 to £88,185
  • Handling
  • Strong engine range
  • Comfortable cabin
  • No real benefit over an X5
  • High running costs
  • Poor ride in X6M

Diesel still rules in this class for fuel economy and CO2, particularly when there’s no plug-in hybrid available. That leaves the xDrive 30d as the most frugal of the X6 range, capable of 38.7-42.2mpg depending on specification, with corresponding CO2 figures of between 176 and 190g/km. Next up is the 40d, whose 36.2-38.7mpg numbers are surprisingly not too far behind despite the extra output - it’s still using essentially the same 3-litre inline six diesel engine, just in a different state of tune. CO2 here is quoted as 191-203g/km, again depending on factors like wheel and tyre size.

The petrols will guzzle slightly more than their diesel counterparts both in the lab and on the road. For the 40i that means 28.8-31mpg and CO2 of 207-221g/km, while the M50i registers 24.6-25.2mpg and 257-263g/km of CO2. If the X6M Competition topped the tree for performance then it’s somewhere underground in terms of economy, with slightly terrifying WLTP combined economy figures of 12.5-12.7mpg and entire clouds of CO2 exiting the tailpipes at a rate of 287 to 293 grams every kilometre.

With all X6s falling over the £40,000 VED threshold, all are subject to the £325 per year surcharge for the first five years of taxing your vehicle. At the lower end of the CO2 range the 30d will be least expensive to tax, its 176g/km corresponding to £870 in the first year (so £1,195 in the first year including the surcharge), while the X6M’s whopping 293g/km puts it in the top £2,175 bracket, or £2500 including the surcharge. All will cost £475 per year for the next four years. Equally, all X6s fall into the top 37% BIK band for tax years from 20/21 to 22/23.

Insurance groups

Insurance premiums will be high whichever X6 model you opt for. In fact, the 30d version in Sport trim is the only X6 not to be in the highest group 50, although you probably won't save too much as it sits in group 49.


Customers should see pretty decent residual values for the the X6 over three years and 36,000 miles of ownership. Our expert data suggests that, on average, the coupe-SUV should retain around 55% over this period, with the 30d models performing the best at 56-57%.

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