In the early 2000’s, BMW impressed the world with a naturally-aspirated engine that packed 100 horsepower per liter and it powered the E46 BMW M3. At the time, such a specific power output was unheard of in a car as relatively inexpensive as the M3. If you wanted 100 hp/liter in a naturally-aspirated, you needed to buy something like a McLaren F1. However, not only did BMW do it in an M3 but it might have actually done it almost a decade earlier, in the E34 BMW M5.

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Now before you jump down my throat and mock my supposed lack of BMW knowledge, let me mention that we know the E34 M5 did not have 100 hp/liter. Even its bigger 3.8 liter inline-six make 335 hp, or less than 100 hp/liter. However, according to this video, there was a bit of a top-secret M5 produced that packed a whopping 400 PS (metric horsepower — in traditional mechanical horsepower, it’d be around 394 hp), giving it more than 100 hp/liter.

For some reason, though, it seems as if BMW both produced and sold this car in secret. There’s no concrete evidence that such a car ever existed, save for a few enthusiasts who’ve followed its supposed existence for awhile now, as BMW has yet to comment on it. With the VIN number that it’s said to have, we can discern that it is, indeed, an E34 BMW M5 that was built on a typical E34 chassis, used a standard gearbox and was, otherwise, rather ordinary. However look a little further into its VIN info and you’ll soon learn that BMW claimed it to have 400 PS.

BMW E34 M5 photos 28 830x553

Apparently, this super-secret E34 M5 has been around the world a bit, having said to be first been sold in Dubai but and then bounced around after that. Though, there’s no real proof such a car has ever actually existed, aside from some people saying it has and one enthusiast who claims to have owned it. Without getting the car and putting on a dyno, though, there’s no way to know if it actually had 400 hp or not.

To be honest, it’s not crazy to think that BMW made such a thing in secret. The Bavarians have done such things in the past, having developed both an E31 BMW M8 and an E46 BMW M3 Touring, just to name a few. So it’s possible that BMW made a development mule with 400 hp, just as a bit of a test, and then sold it internally to a BMW exec or maybe a member of some royal family (hence the Dubai theory). Personally, I love these stories of top-secret projects that rarely, if ever, see the light of day. So check this video out and learn about what could be an extremely interesting BMW.