BMW 5 Series E28: Mercedes OM 606 Diesel swap claiming 500 cv

Lifting the bonnet, it is impossible to miss. Instead of the 1.8-litre petrol inline four that this 1987 BMW 5 Series E28 ought to have, there is a Mercedes Diesel straight-six from BMW’s arch-rival.

You cannot help but wonder what persuaded someone to fit Stuttgart’s OM 606 block (1993–2001) into this Munich-built saloon, but your attention is quickly pulled to the advertised power figure: 500 cv!

As the story goes, in standard form the OM 606 never produced more than 177 cv from its six pistons and 3.0-litre capacity - so how did this Diesel engine, now installed in a BMW 5 Series E28, almost triple its output?

Let the… transformation begin

According to the seller, the engine has been heavily reworked: it now runs a BorgWarner S300 turbocharger (up to 3 bar of boost), a new fuel pump, a bespoke stainless-steel exhaust system (76 mm), a replacement radiator (from an E36 M3), and an external wastegate valve.

To get all of that Diesel muscle down onto the tarmac, the BMW 5 Series E28’s transmission also had to go. The solution was a six-speed manual gearbox from a Mercedes-Benz C-Class 220 CDI (year not specified), paired with a strengthened Sachs clutch kit and a flywheel made specifically for this conversion.

A custom propshaft was fabricated from scratch too, and at the rear this 5 Series now features a limited-slip differential (with a 2.93:1 ratio). Of course, to make this heretical drivetrain fit into the “bimmer”, bespoke engine and gearbox mounts had to be made - and significantly reinforced - no surprise…

Naturally, the chassis has been uprated to cope with it all: the braking system comes from a BMW 540i (E34), every bushing has been replaced with polyurethane items (Polybush), and suspension duties are now handled by BC coilovers.

“Terrifyingly fast”

According to the owner, despite the “Frankenstein monster” nature of this creation, he says it “drives perfectly, has surprisingly good handling and is terrifyingly fast”.

To finish it off, the humble 518i look has been upgraded with an M535i body kit, BBS wheels finished in powder coating, and a recent respray in the vivid red you can see in the pictures.

Would you buy it?

This bizarre yet captivating machine is located in the United Kingdom, has a valid MOT, and is listed on eBay for £16,500 (around €19,260). For now, nobody has bid above the reserve price.

The owner/seller claims he has covered 16,000 kilometres in this BMW 5 Series E28 with a “devilish” Mercedes-Benz Diesel engine since the conversion and, in his words, “it’s crazy”. The car itself, however, is showing roughly 300,000 kilometres.

Would you take the risk?