BMW M10
BMW M10 (1962-1988): specifications, reliability, common problems and every car that has it.
- Layout
- Inline-4 NA petrol
- Produced
- 1962–1988
The M10 is the engine BMW built for twenty-six years and roughly 3.5 million cars. It powered
the New Class saloons that saved the company in the 1960s, the 2002, the first two 3 Series, and
— in turbocharged racing form — the Formula One car that won the 1983 world
championship. Almost every four-cylinder BMW before 1988 has one.
What the M10 is
A cast-iron-block inline-four with an aluminium cylinder head and a single chain-driven
overhead camshaft, built in displacements from 1.5 to 2.0 litres. Its defining feature is the
head: a crossflow design with the valves inclined in a hemispherical chamber, which in 1961 was
racing practice rather than saloon-car practice.
That head is why the engine lasted. It gave the M10 room to grow that its contemporaries did
not have, and it is the reason two very different things descend from it: the
S14 of the E30 M3, which is an M10 block with an M division
four-valve head, and the 1.5-litre turbocharged racing engine BMW ran in Formula One.
Where it appears in our records
| Model | US model years | Cylinders | Displacement | Combined mpg |
|---|---|---|---|---|
| 3 Series (318i) | 1984–1985 | 4 | 1.8 L | 21–24 |
One entry, and it marks the end of the engine rather than its life. United States fuel
economy records begin in 1984 and the M10 finished in 1988; the 2002, the 320i and the E21 cars
that made the engine’s reputation are all earlier than any government dataset we use.
Our specification pages begin in 1989, one year after the M10 stopped, so there are none for
it at all. This is the widest gap between an engine’s importance and what we can document about
it from a source, and we would rather say that plainly than fill the space.
The engine behind the 2002
The 2002 is the car most often credited with establishing BMW in America, and its engine is
this one: a two-litre M10 in a light two-door saloon. The
2002 pages in this archive cover the car itself.
There is a naming trap worth knowing about. BMW has a model called the 2002 and a model year
called 2002, and they are different things — something our own file-matching got wrong
once, filing a 2002 M3 brochure under the model “2002”. If you are searching this site for the
car, the model archive is the place to start.
From saloon engine to Formula One
The turbocharged 1.5-litre BMW ran in Formula One in the early 1980s was built on the M10
block. Nelson Piquet won the 1983 drivers’ championship with it, and the
1985 L7 brochure in this archive mentions the fact
directly — it describes “the spectacular success of the BMW Formula 1 power unit which,
only in its second year of racing, helped Nelson Piquet win the 1983 Grand Prix World
Championship”, alongside “the first computer-controlled engine introduced by BMW in 1979”.
That is BMW writing about its own racing programme in a sales brochure for a luxury saloon,
two years after the fact, and it is the only period source we hold that touches this engine at
all.
What we do not publish
No reliability rating and no power figures. The NHTSA complaint database records faults
against a vehicle rather than an engine, and for cars of this age there is nothing
usable in it. Rated power appears in United States certification records only from 1998, ten
years after the M10 finished.
Common questions
Which BMWs have the M10?
Over its life: the 1500, 1600, 1800 and 2000 New Class saloons, the 1602 and 2002, the E21
3 Series in 316, 318i and 320i form, the E30 316i and 318i, and the E12 and E28 518i. In the
United States records we hold, only the 1984–1985 318i appears.
How much horsepower does the M10 have?
It depends entirely on displacement, year and market, and we do not publish a figure because
no source we hold carries one. A period brochure would close this gap and we have none from
before 1985.
Is the M10 the same as the M40?
No. The M40 replaced it from 1987 with a belt-driven camshaft and
a different head design. They are separate engines a generation apart.
What is the connection to the E30 M3?
The S14 in the E30 M3 uses an M10-family block with an M division
four-valve head. The bottom end of the most collectible M3 is, in origin, a saloon-car engine
from the 1960s.
What replaced the M10?
The M40 in 1987 and, alongside it, the
M42 twin-cam four from 1989.
Sources
The Formula One and Digital Motor Electronics passages are quoted from the
1985 BMW L7 brochure in this archive. Cylinder count,
displacement, model years and fuel economy from EPA fuel economy data.