BMW 8 Series trim comparison
2026 BMW 8 Series 840i xDrive vs M850i xDrive
The 8 Series 840i xDrive starts at $107,500 while the M850i xDrive is $120,300. That $12,800 gap buys 7 meaningful differences.
This trim jump changes the engine from 3.0L I6 Turbo to 4.4L V8 Turbo. Everything else is secondary to whether that powertrain difference matters for how you drive.
Start with the 840i xDrive if the 3.0L I6 Turbo already feels sufficient for the way you drive. Step up to the M850i xDrive only when the 4.4L V8 Turbo powertrain is the reason you are moving higher in the lineup.
If you are budgeting this move monthly, the jump from the 840i xDrive to the M850i xDrive is about $225/month on a 60-month loan at 6.5% APR with 10% down. That works out to roughly $13,500 more by the time interest is counted. The payment only makes sense if that different powertrain matters to the way you actually drive, tow, or live with the vehicle.
Lock one trim, change the other side, and move through exact pair pages without resetting back to the full lineup every time.
Who notices the difference
The higher trim starts to make more sense when you are specifically shopping for the stronger powertrain, not just more trim content.
When both feel the same
Both the 840i xDrive and M850i xDrive share the same 8-speed shiftable automatic transmission and identical wheelbase and body dimensions.
The upgrade math
You are paying $12,800 for 6 measurable differences, which works out to about $2,133 per change.
Key Differences at a Glance
This is the fast read: price, power, efficiency, and the feature flips most likely to change the answer.
Every Difference, Side by Side
This is the full read behind the quick decision signals above: the complete hardware, comfort, and equipment story. 7 specification differences, 1 shared.
Full Specification Comparison
Specifications reflect available data as of early 2026. Confirm details with an authorized dealer before purchasing.
| Spec | 840i xDrive | M850i xDrive |
|---|---|---|
| Pricing | ||
| MSRP | $107,500 | $120,300 |
| Powertrain | ||
| Engine | 3.0L I6 Turbo | 4.4L V8 Turbo |
| Horsepower | 335 hp | 523 hp |
| Torque | 369 lb-ft | 553 lb-ft |
| Transmission | 8-speed shiftable automatic | 8-speed shiftable automatic |
| Drivetrain | AWD | AWD |
| Fuel Economy | ||
| City MPG | 21 | 17 |
| Highway MPG | 29 | 24 |
| Combined MPG | 24 | 19 |
| Fuel Tank | 18.0 gal | 18.0 gal |
| Annual Fuel Cost (EPA) | $2,400/yr | $3,050/yr |
| Dimensions | ||
| Curb Weight | 4,266 lbs | 4,691 lbs |
| Wheelbase | 111.1" | 111.1" |
| Length | 191.2" | 191.2" |
| Width | 74.9" | 74.9" |
| Height | 53.0" | 53.0" |
| Warranty | ||
| Bumper-to-Bumper | 4yr/50k | 4yr/50k |
| Powertrain | 4yr/50k | 4yr/50k |
| Corrosion | 12yr/unlimited | 12yr/unlimited |
| Roadside Assistance | 4yr/unlimited | 4yr/unlimited |
Data sources: licensed third-party automotive data, EPA fueleconomy.gov, NHTSA, and official manufacturer materials. Values marked est. are estimated.
2026 BMW 8 Series 840i xDrive vs M850i xDrive Questions Shoppers Ask
Use this page for the direct trim answer, then zoom back out to the BMW 8 Series lineup, the BMW brand hub, the Sports Cars, the how to pick a trim guide, or our mid-trim value research when you need the bigger shopping path behind this one matchup.
How much more does the 2026 8 Series M850i xDrive cost than the 840i xDrive?
The M850i xDrive starts at $120,300 compared to $107,500 for the 840i xDrive. That is a $12,800 difference, or approximately $225/month more on a 60-month loan.
Do the 2026 BMW 8 Series 840i xDrive and M850i xDrive have the same engine?
No. The 840i xDrive uses a 3.0L I6 Turbo (335 hp, 369 lb-ft), while the M850i xDrive has the 4.4L V8 Turbo (523 hp, 553 lb-ft). That is 188 more horsepower. Both pair with the same 8-speed shiftable automatic.
Do the 2026 8 Series 840i xDrive and M850i xDrive have the same drivetrain?
Yes. Both come with AWD as standard. The differences between these trims are in features and equipment, not drivetrain.
What warranty does the 2026 BMW 8 Series come with?
All 2026 BMW 8 Series trims, including both the 840i xDrive and M850i xDrive, come with BMW's standard warranty: 4yr/50k bumper-to-bumper and 4yr/50k powertrain coverage. Warranty does not vary by trim level.
Is the 2026 BMW 8 Series M850i xDrive worth $12,800 more than the 840i xDrive?
The $12,800 buys the 4.4L V8 Turbo. If that powertrain matters for how you drive, yes. If not, the 840i xDrive does the same job for less.
Which 2026 BMW 8 Series trim gets better fuel economy, the 840i xDrive or the M850i xDrive?
The 840i xDrive is the more efficient of the two at 24 combined MPG, versus 19 for the other trim. That matters most if you are balancing running costs against the extra power, drivetrain, or comfort equipment tied to the pricier trim.
The Full Story Behind This Price Gap
Use the direct answer above for this exact matchup, then use these guides to understand whether you are really looking at a feature step-up, a package shuffle, or the point where the lineup starts changing in a meaningful way.
What $12,800 Gets You
The 8 Series M850i xDrive is a clear upgrade over the 840i xDrive. The $12,800 price increase gets you the 4.4L V8 Turbo engine (+188 hp) -- real functional changes, not just cosmetics.
840i xDrive vs. M850i xDrive: Day-to-Day
The M850i xDrive gets the 4.4L V8 Turbo, which changes the character of the car. That means 188 more horsepower and 184 more lb-ft of torque. A significant jump that changes the driving experience. The cost of that extra capability is roughly 5 fewer combined MPG.
Fuel Economy Comparison
The 8 Series 840i xDrive gets 5 more combined MPG. At $3.50/gallon and 12,000 miles/year, that saves roughly $461 per year or $2,305 over five years of ownership.
Summary
$12,800 more for the 8 Series M850i xDrive gets you 6 real differences. At $225/month more, the question is whether those specific changes are things you will use regularly.
Trim-Matched Accessories
These add-ons are split by trim intent so the recommendations follow the actual use case, not just the same repeated product block.
BMW 8 Series 840i xDrive
Value-trim add-onsThese picks fit the 840i xDrive best when the goal is covering the daily-use gaps without paying up to the next trim.
BMW 8 Series M850i xDrive
Step-up trim add-onsThese picks suit the M850i xDrive when you want the accessories to match the nicer cabin, broader utility, or more premium use case.
As an Amazon Associate, TrimAtlas earns from qualifying purchases.
Specifications shown combine licensed third-party automotive data with official manufacturer, EPA, and NHTSA source material for the 2026 model year. Actual pricing, features, and availability may vary by region and dealer. Always confirm details with an authorized dealer before making a purchase decision. TrimAtlas is not affiliated with BMW or any dealership.
Page updated 2026-03-18. Verify equipment, pricing, and regional availability with the manufacturer or dealer.