BMW X3 M40i explained: the straight-six performance SUV
The BMW X3 M40i combines a straight-six with SUV practicality. The B58 engine, xDrive and M Sport differential, practicality, how it compares with the X3 M, running costs and buying tips.
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The BMW X3 M40i is the M Performance version of the G01 X3, one of BMW's most popular SUVs. Introduced in 2017, it combines a 3.0-litre straight-six, xDrive all-wheel drive and sharper chassis tuning with the space and practicality of a mid-size SUV.
It also formed the basis for the X4 M40i, a coupé-style version. For many families, it offers the best balance of performance, comfort and usability in the X3 range. In this article we explain the engine, the chassis, practicality, how it compares with the X3 M and what to check when buying one.
The first X3 M Performance model
The G01 X3 M40i was the first M Performance version of the X3. It sat above the regular six-cylinder and four-cylinder models and below the full X3 M, which arrived later.
The car was designed to deliver strong performance for drivers who need an SUV but do not want to give up driving pleasure. It quickly became one of the most popular M Performance models, especially in markets where SUVs dominate the premium segment. Our article on BMW M vs M Performance vs M Sport explains where M Performance models fit.
The BMW X3 M40i engine
The BMW X3 M40i uses the B58 3.0-litre straight-six with a single twin-scroll turbocharger. It produces around 360 hp in many markets, with strong torque from low revs.
The engine is combined with an eight-speed Steptronic automatic gearbox. Mild hybrid technology was added in some markets during production. Our comparison of the N54, N55 and B58 explains the B58 engine family.
Chassis and drive
The X3 M40i has several features that set it apart from regular X3 models:
- xDrive all-wheel drive with a rear-biased setup.
- An M Sport differential on the rear axle on many cars, improving traction and agility.
- Adaptive M suspension with different driving modes.
- M Sport brakes with larger discs.
- Variable sport steering.
The result is an SUV that feels agile and responsive on twisty roads while remaining comfortable on long journeys.
Practicality
The X3 M40i keeps all the practicality of the X3:
- A large boot with a split-folding rear seat.
- Comfortable space for five people.
- Towing capability in many markets, useful for trailers and caravans. Check the vehicle documents for the approved trailer weight.
- High driving position and good visibility.
It is an excellent family car for drivers who also enjoy driving.
With suitable winter tyres and xDrive, it is also a capable car in snow and on poor roads. Our article on BMW winter tyres explains how to choose tyres for the cold season.
X3 M40i vs X3 M
Compared with the full X3 M:
- Engine: the X3 M uses the S58 M engine with much more power. Our article on the BMW S58 engine explains it.
- Chassis: the X3 M is firmer and more focused.
- Comfort: the X3 M40i is more comfortable in daily driving.
- Running costs: the X3 M40i is cheaper to run and insure.
For most buyers, the X3 M40i offers more than enough performance with better comfort.
X4 M40i
The X4 M40i shares the drivetrain and much of the technology with the X3 M40i, but with a sloping coupé-style roofline. It offers a sportier look in exchange for slightly less rear headroom and boot space.
Choose the X3 for maximum practicality and the X4 for style.
Both models are available with similar equipment packages. Popular options include the Head-Up Display, a panoramic roof, a high-end audio system and Driving Assistant Professional. Our articles on the BMW Head-Up Display and Driving Assistant Professional explain these features.
Running costs and maintenance
The X3 M40i is relatively affordable to run for a performance SUV, but costs are higher than for regular models:
- Fuel consumption depends on driving style and use.
- Tyres and brakes wear faster on a heavy, powerful car.
- Servicing should use the correct oil and follow the service schedule. Our article on BMW Condition Based Service explains the system.
- Gearbox and xDrive maintenance, such as fluid changes, can extend the life of the drivetrain. Our article on BMW transmission fluid explains why.
A healthy B58 engine is generally robust.
Buying tips
When buying a used X3 M40i:
- Check the service history and oil changes.
- Look for coolant and oil leaks, which can occur on some B58 engines.
- Test the xDrive system for noises and smooth operation when manoeuvring.
- Check tyres and brakes.
- Test all electronic features, including driver assistance and infotainment.
Our complete checklist for buying a used BMW covers other checks. The newer generation of the X3 continued with a more powerful top model under a different name.
BMW X3 M40i key facts
| Item | Details |
|---|---|
| Internal code | G01 X3, G02 X4 |
| Launched | 2017 |
| Engine | B58 3.0-litre straight-six, single twin-scroll turbo |
| Power | Around 360 hp in many markets |
| Gearbox | 8-speed Steptronic automatic |
| Drive | xDrive with M Sport differential on many cars |
| Position | Between regular X3 models and the X3 M |
Frequently asked questions
Is the BMW X3 M40i an M car?
It is an M Performance model, not a full M car like the X3 M.
How much power does the X3 M40i have?
Around 360 hp in many markets.
Is the X3 M40i good for families?
Yes. It offers space, practicality and towing capability with strong performance.
What is the difference between the X3 M40i and X4 M40i?
They share the drivetrain. The X4 has a coupé-style roof with less rear headroom and boot space.
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