Tuning · BMW X3 M40i (G01 / G45)
X3 M40i
B58 Gen 2
The performance X3 with the Gen 2 B58 underneath. Hand-calibrated from Stage 1 to a fully bespoke big-turbo build. Choose your package, send your build to Samuel, and get a tune that fits the way you actually drive.
Engine
B58 Gen 2
Stock
374 bhp · 500 Nm
Stage 3 ceiling
374 bhp
About this tune
The X3 M40i runs the B58 Gen 2 in G01 (2017-2024 LCI) and G45 (2024-present) SUV form. Stock is 374 bhp / 500 Nm with xDrive standard. Same engine, gearbox and ECU as the M340i in a taller, heavier body, the X3 M40i Stage 1 / Stage 2 transformation is one of the most noticeable in the BMW SUV range precisely because the kerb weight gives the torque more work to do. The X3 M40i is widely tuned in the UK and a strong choice for owners who want M-Performance pace in a family-sized BMW.
BMW X3 M40i tuning
An X3 M40i spends its life doing everything: commuting, dogs, tip runs, holidays. That is precisely why it is one of the most tuned SUVs in the UK. The G01 and G45 carry the same drivetrain as the M340i under a taller, heavier body, and it is that weight that makes the remap so transformative. Give the B58 more torque and the X3 stops feeling like a quick SUV and starts moving like the sports saloon it borrowed its drivetrain from.
Factory output is 374 bhp and 500 Nm, respectable but working hard against the kerb weight. Stage 1 raises the calibration to 440 bhp and 680 Nm on standard hardware, and in a car this size the extra 180 Nm is the headline: the X3 pulls from low revs the way owners always assumed it should. Stage 2 adds a downpipe and intake and moves the target to 480 bhp and 700 Nm.
The platform's 1,000 bhp ceiling applies here too, with hybrid and full-frame turbo builds calibrated bespoke, though few X3s go that far. Every stage is handled remotely: Samuel writes the map for your specific car, delivers it through bootmod3, MHD or MG Flasher within 24 hours, and you flash it on the driveway. Your original file is retained, so the car returns to stock whenever needed.
Configurator
Build your X3 M40i tune
Choose your stage — Stage 1, Stage 2 or Stage 3 — add the options that fit your car, and send the full build to Samuel for a custom remote remap. He'll quote, schedule, and personally calibrate within 24 hours of confirmation.
Add a stage or add-on
£0
Engine guide
BMW X3 M40i tuning, stages, hardware and what to expect from the G01 B58 Gen 2
The X3 M40i runs the B58 Gen 2 in G01 (LCI) and G45 (post-2024) SUV form, the same revised 3.0-litre single-turbocharged inline-six fitted to the M340i, M440i, Z4 M40i and Toyota Supra 3.0. From the factory, BMW set the X3 M40i at 374 bhp / 500 Nm; the hardware ceiling sits considerably higher. BMW X3 M40i tuning with Samuel applies the same Gen 2 Stage 1 / Stage 2 map family, with a calibration that accounts for the X3's higher kerb weight and SUV ride height.
Stage 1
440 bhp · 680 Nm
No hardware required. The MG1CS003 DME is flashed via the OBD port. BMW X3 M40i Stage 1 unlocks 440 bhp and 680 Nm from the OEM hardware (up from 374 / 500 stock). The BMW X3 M40i G01 tuning starting point, the most cost-effective change you can make to the SUV, and the difference is immediately obvious given the X3's weight.
Every X3 M40i tune Samuel produces is calibrated individually for the specific car, fuel grade and installed hardware, not a base map loaded and left. BMW X3 M40i tuning done correctly accounts for the SUV chassis weight, xDrive calibration and UK fuel quality; the map is reviewed against your data logs after the first flash and revised before sign-off.
Compatibility
Platform and hardware compatibility
Bootmod3 (BM3)
Full B58 Gen 2 support on the MG1CS003 DME across every Gen 2 chassis (M340i, M440i, M240i G42, Z4 M40i, X3/X4 M40i, Supra 3.0). OBD-port flashing, realtime monitoring via the BM3 app. The most widely used platform for B58 Gen 2 tuning.
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MHD
Full B58 Gen 2 support. Suitable for Stage 1 and Stage 2. Strong data-logging toolset and active community support.
Read more →
MG Flasher
Full B58 Gen 2 support. Clean interface and reliable flash process. A common alternative to BM3 for owners who prefer the MG ecosystem.
Read more →
xHP Flashtool
Compatible with the ZF 8HP gearbox fitted to every B58 Gen 2 chassis. Gearbox calibration matched to the ECU map, strongly recommended at Stage 2 and above where torque jumps significantly. Available as an add-on.
Read more →
ECU: MG1CS003 DME across all B58 Gen 2 production. Accessible via OBD for Stage 1 and Stage 2; bench-flash only required for some Stage 3 hybrid setups.
X3 M40i specs & stage targets
BMW X3 M40i tuning at a glance
- Engine
- B58 Gen 2
- Body styles
- G01 SUV (LCI) · G45 SUV (post-2024)
- Chassis codes
- G01 / G45
- Production
- 2017–2024
- Drivetrain
- xDrive
- Gearbox
- 8-speed ZF automatic
- Stock output
- 374 bhp · 500 Nm
- Tuning ceiling
- ~1000 bhp on the right hardware
| Stage | Target |
|---|---|
| Stage 1 | 440 bhp · 680 Nm |
| Stage 2 | 480 bhp · 700 Nm |
| Stage 3, Hybrid Turbo | 550-1000 bhp depending on spec |
| Stage 3, Big Turbo Kit | 550-1000 bhp depending on spec |
FAQ
X3 M40i tuning — frequently asked questions
The opposite: it is why the transformation is so obvious. The heavier the car, the harder 180 extra newton-metres works, and Stage 1's jump from 500 to 680 Nm changes how the X3 gets down a road far more than the bhp figure suggests. Mid-range pulling power is where an SUV lives, and that is exactly where the gain sits.
This page covers both generations, the G01 built from 2017 to 2024 and the G45 from 2024 onwards. Both run the B58 Gen 2 with xDrive. Confirm your body code and model year when ordering and Samuel builds the file against the correct ECU and hardware for your generation of X3.
The requirement matches the rest of the B58 Gen 2 range: a downpipe, meaning an OPF delete on OPF-equipped cars, and an intake. Together they let the stock turbo breathe well enough for the 480 bhp and 700 Nm calibration. The intercooler, fuelling, gearbox and xDrive hardware all stay as BMW built them at this stage.
That is the intended use. The map changes nothing about cold starts, servicing intervals or everyday drivability. Light-throttle running feels standard and the extra performance only appears when asked for, because Samuel calibrates for smooth, progressive delivery rather than a switch-like hit. Passengers notice nothing until you do it deliberately.
Yes. The original calibration is saved before your first flash and stays yours. Flashing back to stock takes minutes through the OBD port with the same bootmod3, MHD or MG Flasher tool you tuned with, and the process can be repeated as often as needed over the life of the car.
Keep exploring
Keep exploring X3 M40i tuning
Other B58 Gen 2 models we tune: M240i, M340i, M440i, Z4 M40i, X4 M40i, Supra 3.0.
Engine guide
B58 Gen 2 tuning
Every B58 Gen 2 BMW we calibrate, with the full Stage 1, 2 and 3 breakdown for the engine.
Learn moreStages
Stage 1 & Stage 2 explained
What separates Stage 1 from Stage 2 on the X3 M40i, the real-world gains and the hardware each one needs.
Learn morePricing
How tuning is priced
How the licence, off-the-shelf maps and custom calibration are priced. We quote your exact spec, never a fixed menu.
Learn moreGuide
What is bootmod3?
New to remote flashing? A plain-English explainer on the platform and how a custom map reaches your car.
Learn more