BMW 8 Series review - MPG, CO2 and running costs

Tiresome though the news may be, if you’re forced to factor running costs into your new car purchase, it’s highly unlikely the M850i is the right model for you. BMW says it will cover up to 25.2mpg on the (WLTP test) combined cycle, but if you’re even slightly tempted by its phenomenal performance, the true MPG figure will drop like a stone. Driven briskly, we certainly wouldn’t be surprised by MPG in the teens – high or low.

Equally the 255g/km of CO2 emitted under test conditions is unlikely to match real world use, but at least that won’t cost anything more from a financial perspective. The car is in the maximum Benefit-in-Kind bracket, too, so you’ll be whacked by the tax man if you run an M850i on the company, although it’s a similar story for any high-performance company car – unless it’s a hybrid or electric vehicle.

The BiK rate is the same for the diesel 840d, but 183g/km of CO2 (depending on wheels and bodystyle) is an improvement. The potential mixed driving economy of up to 40.4mpg (in the Coupe) will be less hard on your pocket, too. The extra economy pays dividends with range – you’ll be spared filling up so often on trans-continental jaunts as the range is a realistic 500 miles. In all cases, the Coupe models are most efficient and the heavier Gran Coupe is the least.

The go-faster M8 Competition returns 25.4mpg in Coupe and Gran Coupe guise, and 25.2mpg as a Convertible.

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Insurance groups

The Association of British Insurers has assessed both the new 8 Series models as insurance group 50, which means sky-high premiums for anyone not on a multi-car company-type policy, or on very good terms with their broker. It’s no surprise though, as all high performance and luxury cars are expensive to cover.

Depreciation

Initial residual values for the 8 Series were strong, although this has waned slightly over time, with expert data suggesting an average value of 43% will be retained over 3 years and 36,000 miles. Buyers should be wary of ticking the expensive Ultimate Pack option. It costs between £15,000 and £22,000 and, although it brings many extra features, it does nothing for long-term values. These cars are expected to hold onto around 39% of their list price over the 3 year period.