What the BMW M70 Is
The BMW M70 holds a special place in the company's history as its first twelve-cylinder engine of the modern era, introduced in 1987. Displacing 5.0 liters and producing 300 horsepower in naturally aspirated form, the M70 established BMW as a serious rival to the established V12 luxury builders. It was engineered for effortless, turbine-like power delivery rather than outright aggression, giving BMW's top flagship a level of refinement the brand had not previously offered.
The launch of the M70 marked a deliberate step up the model ladder for BMW, and it remains a landmark in the company's engineering DNA. If you're researching a specific car, our VIN decoder can help confirm which powertrain a chassis originally left the factory with.
Architecture and Engineering
The M70 is a 60-degree V12 with an all-aluminum block and cylinder heads, essentially conceived as two inline-six units sharing a common crankcase — a philosophy rooted in BMW's long inline-six tradition seen in engines like the M30 and M20. Each bank carries a single overhead camshaft operating two valves per cylinder, a relatively conservative valvetrain choice that prioritized smoothness and reliability over peak output.
- Configuration: Naturally aspirated 60-degree V12
- Displacement: 5.0 liters
- Output: 300 hp
- Construction: Aluminum block and heads, SOHC per bank
Notably, the M70 used two separate engine control units — effectively one for each cylinder bank — allowing the engine to run, in a limp-home sense, on a single bank if one system failed. This redundancy speaks to the engineering ambition behind the design.
Which BMWs Used It
The M70 powered the flagship BMW models of its era, most famously the 750i and 750iL variants of the E32 7 Series, and it later found a home in the E31 8 Series grand tourer badged as the 850i. In these applications the V12 delivered the serene, high-speed cruising character expected of BMW's most expensive cars.
Reliability, Known Issues and Ownership Notes
The M70 is generally regarded as robust, but its complexity demands respect. Prospective owners should keep the following in mind:
- Dual everything: Two ECUs, two throttle systems and extensive wiring mean diagnosis takes patience and V12-specific expertise.
- Cooling and seals: Aging cooling components and gaskets are common attention points on high-mileage examples.
- Deferred maintenance: Because these cars have often changed hands cheaply, service history matters more than the asking price.
Compared with BMW's simpler four- and six-cylinder engines of the period, such as the M40 and M10, the M70 is a far more involved ownership proposition — but for enthusiasts it delivers a driving experience those smaller engines simply cannot match.