Supercars.net

As the high-profile M3 became the most successful touring car of all time, its civilian version became increasingly exciting. To stay on par with seasonal developments, BMW Motorsports released updated versions each year. These cars mimicked the performance changes required to keep the Group A race car ahead of the competition. The last and most potent evolution of these was the M3 Sport Evolution.

When the Touring rules in Germany and France increased capacity limits to 2.5 liters in 1990, BMW endowed the M3 with its largest engine. In order to make full use of the 2.5 liter limit, they not only increased the stroke of the 2.3 liter unit from 84 to 87 millimeters, but also increased the bores of the four cylinders from 93.4 millimeters each to 95.5 millimeters. This reduced the width between the cylinders to just 4.5 millimeters. But success proved them right. The engines withstood the stresses and strains of touring car racing even at maximum output without any problem.

To meet homologation, BMW released a road-going model that featured this new 238 bhp, 2.5 liter engine which used sodium-cooled exhaust valves, a larger intake tract and a signature red spark plug wires. Aside from the engine, each car had an adjustable front apron and rear wing, as well as a special interior with Sparco seats and suede controls. There was no air-conditioning or electric windows and each of the 600 cars had a numbered plaque on the centre console.

Story by BMW & Supercars.net

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