This BMW M Sedan Was So Secret Even Your Dealer Didn't Know About It
Fully restored, this rare 1979 BMW 533i is coming up for auction
Walk into a BMW dealership in 2026 and the salesman will happily sell you an M version of pretty much any car in the showroom, from the little 2 Series coupe right up to the 7 Series luxury sedan. But things were different in the 1970s. Try to order a 533i, for example, and it's possible your average dealer would tell you there was no such thing. But there was. You just needed to know who to ask.
The 5 Series sedan was born in 1972, the same year as the Motorsport department, and by 1974 the small M team was pulling cars from the main Dingolfing production line, and diverting them to its own workshop. This was two years before BMW South Africa created the 530 Motorsport Limited Edition to homologate its race cars, almost five years before the launch of BMW M's production M535i, and a whole decade before the world laid eyes on the original M5.
Models like the 525, 528 and later fuel-injected 528i had their 2.5- and 2.8-liter inline-6 motors pulled, and replaced with 3.0- or 3.3-liter sixes from the CS coupe, 6 Series, and big E3 sedan. Hottest of those was the 533i, whose 197-horsepower 3.2-liter six took it to 132 mph, making it as fast as a base-model 911.
Born a 525, became a 535i
There was more to BMW M's E12 5 Series conversions than simply a big engine. A five-speed transmission with a dogleg first gear and direct-drive top, a limited-slip differential, sports dampers, and alloy wheels with wider tires were all on the menu. Some owners played it stealthy, leaving their cars looking mostly stock. Others went all in on the Motorsport theme, choosing lurid M graphics and spoilers.
No prizes for guessing which way this Motorsport 5 Series' first owner swayed. It was built in the summer of 1979, by which time BMW M had further improved the recipe, making this a dry run for the 1980 production E12 BMW M535i. The Polaris Silver example up for auction started life as an unassuming 525, but it didn't stay that way for long.
Out came the carb-fed 2.5-liter M30 six, and in went the 3.5-liter version from the 635CSi. That meant 218 hp and a 138-mph top speed. Fat, 14-inch BBS Mahle wheels helped keep the E12's tail glued to the pavement, and a set of Auto Sport Spezialsitze (yes, really) bucket seats kept the driver the right way up.
Now on just its fourth owner, and fully restored, this E12 is being auctioned by Humer Granner in Austria on October 17, 2026. It's being sold with no reserve and an estimated value of €75,000-€95,000 ($84,000-$106,000). I don't know about you, but that looks like a great value considering both the condition, the rarity – it's believed only handfuls were made – and just how significant this car is in terms of BMW M history.
