Second Hand BMW 8 Series Engine

The BMW 8 Series (G14/G15/G16) ran from 2018 onwards, with a mid-cycle refresh around 2022, so there is one main generation to work within rather than a true generational swap. Whether an engine from a pre-2022 car will bolt straight into a post-2022 car depends on whether ancillary mountings or wiring changed at that point, which you should confirm with the breaker against your specific registration. The engine code, found on your V5 or via a VIN check, is the single most reliable way to match a donor unit to your car.

Both cars carry the B58 straight-six petrol engine, so the engine code is your first check — if the codes match, you are starting from the right place. Year within the G15 generation can still matter if there were running changes to ancillaries or engine management, so confirm with the breaker using both your registration and the donor car's registration. Never assume a match purely on badge; always verify the code.

No — the 840d uses a B57 diesel unit and the 840i uses a B58 petrol unit; fuel type fundamentally changes the engine family, so these are not interchangeable. Even if physical space were similar, ancillaries, engine management, and fuelling systems are entirely different. Always source a unit that matches your exact engine code.

M Sport is a cosmetic and chassis trim level on the 8 Series, not a different powertrain, so it does not affect engine fitment at all. An M Sport 840i and a standard 840i share the same B58 engine, meaning a used unit from either will be the same mechanically. You may notice minor cosmetic differences on ancillary covers between cars, but these have no bearing on whether the engine itself fits. The M8, however, uses a different high-performance engine entirely and is a separate model, so do not cross those units.

ECU pairing and immobiliser coding are something you should confirm directly with the breaker or a BMW specialist rather than assume either way, as this depends on how the engine management is set up and what has been included with the unit. Some used engines are supplied with matching ancillaries that ease the process, and some breakers can advise on what is needed. Your engine code and registration are the key details to have ready when you have that conversation.

Body style does not affect engine fitment on the 8 Series; the same engine codes are used across the coupe (G15), convertible (G14), and Gran Coupe (G16) variants where the same powertrain is offered. What matters is matching the engine code, fuel type, and gearbox type, not which body style the donor car or your car happens to be. Confirm the engine code via your V5 or a VIN check and supply that to the breaker.