What is the real-world MPG of a BMW 8 Series?
Owners report an average of 33.5 mpg across all BMW 8 Series engines with data, about 95% of the official combined figure. The engine tables on this page give the figure for each engine and generation.
BMW 8 Series MPG: what owners actually get
Owners report 33.5 mpg from a BMW 8 Series, about 95% of the official figure. On its WLTP-tested engines that is 95%, about typical: the median WLTP-tested car in this 8,216-engine dataset returns 94%. The tables below give the figure for every engine and generation we hold. Add your own at the bottom and the averages get better for the next buyer.
33.5mpg
Real-world average, all engines
95%
of the official combined figure
19–47
Range reported by owners (mpg)
25
Owner submissions
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BMW 8 Series
| Engine | Official (NEDC) | Official (WLTP) | Real MPG | % of official | Owners report |
|---|---|---|---|---|---|
| 840d xDrive | 46.3 | 38.8–44.1 | 37.8 | 91%* | 30.0–46.8 |
| 840i | – | 33.2–34.4 | 36.0 | 107%* | 33.0–40.0 |
| M850i | 28.8 | 24.8–26.9 | 22.3 | 86%* | – |
BMW 8 Series Convertible
| Engine | Official (NEDC) | Official (WLTP) | Real MPG | % of official | Owners report |
|---|---|---|---|---|---|
| 840d | 45.6 | – | – | – | – |
| M850i | 28.2 | – | – | – | – |
BMW 8 Series Gran Coupe
| Engine | Official (NEDC) | Official (WLTP) | Real MPG | % of official | Owners report |
|---|---|---|---|---|---|
| 840d xDrive | – | 38.2–42.8 | – | – | – |
| 840i | – | 33.2–33.6 | 32.2 | 96%* | – |
| M850i | – | 25.9–26.4 | – | – | – |
All figures in miles per gallon (UK). “Owners report” is the spread of individual submissions for that engine. * Measured against the WLTP figure rather than NEDC.
Add your BMW 8 Series Real MPG
What does yours actually do? Read it off the trip computer over a full tank or work it out from litres and miles. No postcode, no sign-up. The more people add, the better the averages get, and this page stays free.
BMW 8 Series fuel economy questions
Why is the BMW 8 Series real MPG lower than the official figure?
Official figures come from a laboratory test cycle, not the road. Cold starts, short trips, hills, load, tyres and driving style all cost fuel the test does not see. A gap of 10 to 30 per cent is normal; a much bigger gap on one engine usually points at a fault, a heavy right foot, or a diesel that never gets warm.
Where did the Honest John BMW 8 Series Real MPG page go?
The site closed in August 2026 and its Real MPG section went with it. This page is where the BMW 8 Series figures now live: rebuilt from the archived dataset, with the official figures kept alongside, and reopened for new submissions.
Looking at a BMW 8 Series right now? Check the advert before you go and see it.
Where the BMW 8 Series figures come from
If you used the Honest John Real MPG section before the site closed in 2026, this is where the BMW 8 Series figures now live. The owner-reported averages above were rebuilt from the archived dataset (archived page, 2026-03) alongside the official NEDC and WLTP figures and new submissions from CarAdCheck readers, and the section is open so they keep improving. Real-world figures also feed the running-cost estimate in our free advert check.
CarAdCheck is not affiliated with Honest John or Volkswagen Financial Services. How we rebuilt Real MPG.
Other BMW models
Before you go and see it
Fuel economy is one line on the BMW 8 Series running-cost sheet. These guides cover the checks that stop you buying the wrong one.
How to haggle for a used car: negotiate the price with what its records showHPI check vs carVertical: which is better, and our pick for a UK carMOT advisories explained: how to check them, and which ones should worry you
All buyer's guides →