Tuning · BMW 320i (G20 / G21)
G20 320i
B48
The entry-point B48 in saloon and Touring form. Hand-calibrated from Stage 1 to Stage 3. Choose your package, send your build to Samuel, and get a tune that fits the way you actually drive.
Engine
B48
Stock
184 bhp · 300 Nm
Stage 3 ceiling
184 bhp
BMW 320i tuning
Nobody buys a 320i expecting to be quick, and that is exactly what makes it worth tuning. The G20 saloon and G21 Touring are the entry point to the current 3 Series range, hugely popular as company cars and family workhorses, and BMW leaves an enormous margin in the factory calibration. Owners come to Samuel because a mapped 320i keeps its anonymous badge while gaining the pace of cars two rungs up the range.
From the factory the 320i produces 184 bhp and 300 Nm. Samuel's Stage 1 calibration lifts that to 280 bhp and 450 Nm on completely standard hardware — a bigger percentage jump than almost any other B48 car he tunes, because the 320i starts from the most conservative baseline. Fit a downpipe and intake and Stage 2 raises the target to 320 bhp and 500 Nm.
The platform does not stop there: with a hybrid or full-frame turbo and supporting fuelling, the 320i can be calibrated to around 500 bhp. Everything is handled remotely — you flash through the OBD port using BM3, MHD or MG Flasher, your hand-built file arrives within 24 hours, and the stock calibration is saved first so the car can go back to factory whenever you want.
Configurator
Build your G20 320i 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 320i tuning, stages, hardware and what to expect from the G20 B48
The G20 320i runs the B48, BMW's 2.0-litre single-turbocharged inline-four in its detuned 184 bhp configuration. The block, head and turbo are identical to the 330i's; only the software calibration and a slightly smaller injector spec separate the two. BMW 320i tuning with Samuel exploits the fact that the 320i ships from the factory with the most conservative software limiter in the modern B48 family, there is significant headroom in the OEM hardware, and Stage 1 alone unlocks more torque than a stock 330i makes. BMW 320i G20 tuning and BMW 320i G21 Touring tuning use the same map; only the build sheet differs for the wagon exhaust geometry.
Stage 1
280 bhp · 450 Nm
No hardware required. The MG1CS003 / MEVD17 DME is flashed via the OBD port, boost pressure, ignition timing, fuel delivery and torque limiters all revised. BMW 320i Stage 1 unlocks 280 bhp / 450 Nm from the OEM hardware (up from 184 / 300 stock), one of the largest single-software gains available on any modern BMW because the factory limiter is so conservative.
Every 320i tune Samuel produces is calibrated individually for the specific car, fuel grade and installed hardware, not a base map loaded and left. BMW 320i tuning done correctly accounts for the G20 chassis weight bias, the 8HP gearbox 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 B48 support across every chassis in the family (320i, 330i, 420i, 430i, 530i, Z4 sDrive20i). OBD-port flashing on the MEVD17 (early) and MG1CS003 (later) DMEs. Realtime monitoring via the BM3 app, the most widely used platform for B48 tuning.
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MHD
Full B48 support. Suitable for Stage 1 and Stage 2 across the family. Strong data-logging toolset for verifying lambda, ignition correction and intake temperatures after each flash.
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MG Flasher
Full B48 support. Clean interface and reliable flash process on the MG1CS003 DME, a common choice for owners who prefer the MG ecosystem.
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xHP Flashtool
Compatible with the ZF 8HP gearbox fitted to every modern B48 chassis (G20 / G22 / G30 / G29). Available as an add-on, strongly recommended at Stage 2 where torque jumps significantly for a 2.0-litre four. Manual-gearbox cars do not need xHP.
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ECU: MEVD17 / MG1CS003 DME across B48 production. Accessible via the OBD port, no bench flash required for Stage 1 or Stage 2.
G20 320i specs & stage targets
BMW 320i tuning at a glance
- Engine
- B48 · 2.0L turbocharged inline-four
- Body styles
- G20 Saloon · G21 Touring
- Chassis codes
- G20 / G21
- Production
- 2019–present
- Drivetrain
- Rear-wheel drive
- Gearbox
- 8-speed ZF automatic
- Stock output
- 184 bhp · 300 Nm
- Tuning ceiling
- ~500 bhp on the right hardware
| Stage | Target |
|---|---|
| Stage 1 | 280 bhp · 450 Nm |
| Stage 2 | 320 bhp · 500 Nm |
| Stage 3, Hybrid Turbo | Up to 500 bhp depending on spec |
| Stage 3, Big Turbo Kit | Up to 500 bhp depending on spec |
FAQ
G20 320i tuning — frequently asked questions
A stock G20 320i leaves the factory with 184 bhp and 300 Nm. Samuel's Stage 1 file raises that to 280 bhp and 450 Nm with no hardware changes at all — the largest relative gain of any B48 model he tunes, because BMW holds the entry car back furthest in software. Delivery stays smooth and factory-like; it is simply a much stronger car everywhere.
Not necessarily. A Stage 1 320i at 280 bhp and 450 Nm comfortably clears the factory output of a 330i, and the car underneath is the same G20 or G21 body. If you already own the 320i, a £350 calibration is a far cheaper route to that performance than changing cars.
A downpipe and an upgraded intake. With those supporting the standard turbo, Samuel calibrates the 320i to 320 bhp and 500 Nm. Nothing else is required at this level — the standard turbo and fuelling operate within their limits at these figures, so the spend stays on the two parts that matter and the calibration behind them.
Samuel builds each 320i map around the fuel you actually run rather than assuming the best case. Higher-octane super unleaded (97–99 RON) supports the strongest calibration and is what he recommends for the full Stage figures; tell him your usual fuel when you order and the file is written to suit it.
To around 500 bhp on the right build. A hybrid turbo with downpipe, intake and supporting fuelling takes the 320i well past the standard-turbo stages, and a full-frame turbo conversion reaches the platform's ceiling. These are bespoke calibrations — send Samuel your full hardware list and he builds the file around exactly what is on the car.
Keep exploring
Keep exploring G20 320i tuning
Other B48 models we tune: 330i, 330e, G22 420i, 430i, 530e, 530i.
Engine guide
B48 tuning
Every B48 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 G20 320i, 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