BMW G70 740i B58 — first impressions and tuning plans

about 1 month ago· 16 posts

Took delivery of a 2025 G70 740i last month. The B58 in this generation makes 380hp stock with the 48V mild hybrid — already feels quick but I know there is more potential in this engine. First impressions: the interior is stunning, the 31-inch Theatre Screen in the rear is insane, and the driving dynamics are surprisingly good for a car this size. The rear-axle steering makes parking effortless and the car feels much smaller than it is at low speeds. Tuning-wise, I am waiting for BM3 or MHD to release support for the latest B58TU2 variant. The ECU encryption on the G70 is more aggressive than previous generations so it might take a while. Has anyone heard any updates from the tuning community on G70 support? Also curious about Bimmercode compatibility — I want to do some basic coding like ambient lighting customization, digital speedo in the HUD, and disabling the seatbelt chime for the passenger seat.

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Replies (2)

CodingChris

29 days ago#1

Bimmercode already has partial support for the G70 — you can do ambient lighting, digital speedo, and most comfort coding. The seatbelt chime disable works too. Make sure you are on the latest Bimmercode version (4.33+) and use the WiFi OBD adapter, not Bluetooth — the G70 requires the faster connection for some modules. For ECU tuning, the B58TU2 in the G70 uses the Bosch MG1CS201 DME which is the same family as the G80 M3. BM3 has been working on support but the encryption is a challenge. Last I heard from their Discord, they expect G70 support in Q2 2026. In the meantime, some tuners are offering bench-flash solutions where you remove the DME and flash it on the bench — not ideal but it works. Expect 430-450hp on a conservative stage 1 map.

13 posts · 0 rep

LidarLukas

28 days ago#2

The G70 is a tech showcase. I have been playing with the iDrive 8.5 system extensively — the voice assistant is actually usable now, and the integration with BMW Digital Key Plus means you can share your car key via iMessage. For coding enthusiasts, the G70 uses the newest MGU headunit which supports more customization than previous generations. One thing to note: BMW has started locking certain coding options behind their ConnectedDrive subscription. Some features that were previously free to code (like enhanced Bluetooth audio streaming quality) now require an active subscription. This is a trend I expect to continue with newer models. For the Theatre Screen, make sure you update the rear entertainment firmware — the initial version had stuttering issues with 4K content that BMW fixed in a software update.

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