BMW e90 320si, a German four-cylinder that will surprise you

A few days ago we showed you some of the most important homologation cars in history, but today it’s the turn of a model that very few people know. Homologation cars, or what are known as homologation special , are street cars that held the key that allowed their racing counterparts to compete. The BMW 320si is one of them and, at first glance, it is a BMW Serie 3 E90 with wheels signed by BMW Motorsport, but that’s not all…

The BMW 320si was the last homologation car from the Bavarian brand. Only 2,600 units were built in 2006, and it has a very important story to tell you. That said, don’t expect to see them in Spain, since those 2,600 units were sold only in Germany. No, I haven’t made a mistake and swapped the order: it is not a BMW 320is, it is a BMW 320si.

BMW 320si, an E90 to homologate BMW’s participation in the WTCC

BMW Motorsport relaunched its competition programme on this date, 2006, in the WTCC. The brand needed to homologate the participation of its Serie 3 in the touring car world championship and therefore built 2,600 units of the road car that would serve as the basis for its race car. This is how the 320si was born, a four-door E90 Serie 3 with a very special heart, not to mention exclusive wheels and a very discreet badge on the rear tailgate. It also featured a 300 mm diameter braking system, sourced from a BMW 325i.

The engine of this spectacular model was hand-assembled, and the cylinder head was manufactured alongside those of the Formula 1 single-seaters of BMW. The gearbox had no differences compared with a 320i. The engine’s stroke was shorter than that of the 320i, offset by a piston diameter one millimetre larger. The rocker cover was made of carbon fibre with the aim of saving up to ten kilograms of weight and lowering the centre of gravity.

BMW Motorsport also raised the compression ratio and offered 173 CV at 7,000 rpm and 199 Nm at 4,250 rpm. That said, it did not come close to the almost 300 CV of the race version. The powerplant had a very distinctive metallic sound and did not feature Valvetronic variable valve timing, in order to achieve a simpler engine and better behaviour in competition. On paper, it could accelerate from 0 to 100 km/h in 8.1 seconds. It was an agile and balanced car, one of the best examples of perfect weight distribution.

The BMW 320si is a model that, although it is not an BMW M3, is a very special car with a heart signed by BMW Motorsport. One of its weak points is that its engine was rather delicate and the cylinder liners could fail. In addition, it is advisable to use 98-octane petrol, the same as with the BMW M3s of the era, to avoid connecting-rod knock.

Technical specifications of this car

SedanBMW Serie 318 versions · from 50,200 €