BMW M50

The M50 is BMW’s first twin-cam inline-six for ordinary cars, built from 1990 to 1996. It
replaced the single-cam M20, introduced BMW’s variable valve timing
to the mainstream range, and set the pattern every BMW six since has followed.

What the M50 is

A cast-iron-block inline-six with an aluminium head, two overhead camshafts and four valves
per cylinder, in 2.0 and 2.5-litre forms. From late 1992 it gained VANOS — variable
timing on the intake camshaft — and the revised engine is usually written M50TU, for
technische Überarbeitung, technical revision.

Two overhead camshafts and four valves per cylinder were not new in 1990; BMW had used them
on M division engines since the M88. What was new was putting them in a 325i. The M50 is where
that architecture stopped being special.

Where it appears in our records

Four specification pages, all E34 525i, and nothing else. This is the
thinnest coverage of any engine we track relative to how common the engine actually was, and
the reason is entirely about sources: rated power appears in United States certification
records only from 1998, two years after the M50 finished, and our brochure archive holds
nothing from the 1990s at all. The E36 325i, the 320i and the earlier 525i are all outside what
we can document.

What the fuel economy data does give is 19 to 20 mpg combined, which for a 2.5-litre six of
1994 is unremarkable and about what the single-cam engine it replaced returned. The M50’s
advantage was in output, and output is precisely the field we cannot fill from a source.

The engine that set the pattern

Trace BMW’s mainstream six-cylinder engines forward from 1990 and the M50 is where the line
starts: twin cams, four valves, variable timing on the intake side. The
M54 of the 2000s is a direct descendant through the M52; the
N52 that followed added Valvetronic and a magnesium-aluminium block
but kept the layout; the B58 of today is turbocharged and
direct-injected and is still recognisably the same idea.

The M50 is also where the S-prefix distinction becomes clear. The M division’s
S54 and its predecessors are separate engines, not tuned M50s
— a point our guide to engine codes covers,
because the numbering suggests a relationship that does not exist.

What we do not publish

No reliability rating. The NHTSA complaint database records faults against a
vehicle, not an engine, and a 1994 525i record does not distinguish the engine in any
case. We also publish no power or torque figures for the M50: no source we use carries them,
and we do not have a brochure of the period to read them from.

Common questions

Which BMWs have the M50?

The E36 320i and 325i, the E34 520i and 525i, and the E36 M3 in modified S50 form for some
markets. In our United States specification records only the E34 525i of 1994 and 1995
appears.

How much horsepower does the M50 have?

We do not publish a figure, because no record we use carries one for those years. This is a
gap in our sources rather than a gap in the engine’s history, and a period brochure would close
it — we hold none from the 1990s.

What is the difference between M50 and M50TU?

The TU version, from 1992, added VANOS variable valve timing on the intake camshaft. It is
the same basic engine with a revised head and timing arrangement.

Is the M50 related to the S50?

The S50 of the E36 M3 shares the family but is an M division engine: larger, with individual
throttle bodies and a different head. As with every S-prefixed BMW engine, it is not a tuned
version of the ordinary one.

What replaced the M50?

The M52, from 1995, which moved to an aluminium block. The
M54 followed in 2000.

Sources

Model years and fuel economy from EPA fuel economy data, with the source named on every
specification page. No brochure from this period is held in the archive;
if you have one, the submission page explains what to send —
the 1990s are the decade we are missing entirely.