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The most accessible of all homologation specials
2006 BMW 320si

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by GDP

Dec 2021

There is something undeniably appealing about a model which is a homologation special. Perhaps because in a world today where special editions are often created by marketeers to celebrate anniversaries or help sell the run out of a certain model, homologation specials exist for a sole purpose driven by a motor sport regulation requirement.

At one end of the spectrum, when we talk about homologation specials, we think of the pinnacle being the Ferrari 250 GTO and then perhaps the likes of the CLK GTR, Porsche GT1 and other cars such as the Lancia 037 Stradale. The there are Group B cars which are particularly popular at the moment such as the Peugeot 205 T16 and Renault 5 Turbo. But what is there at the other end of the spectrum? Well there is no doubt that this little BMW is one of the most accessible ways to access this exclusive club with a nice low mileage example such as ours recently selling at under 13,000 euros! 


The 320si was launched in 2006 as a necessity in order to homologate a new engine for the World Touring Car Championships for the competitive 320si race car. Marketing and communications of the car where not a huge focus at the time and the units where quickly absorbed by the BMW network to sell on at what was at the time no premium over a 320 M sport standard model. This is what makes this little BMW very special and even today among enthusiasts relatively unknown.

So, what makes this car special? It has the M sport package and suspension which was offered at the time on the e90 3 Series so at a glance, not much. It looks very similar to a 320 or 320d M sport which is a very well resolved Chris Bangle design which combines elegance and practicality with a sporty and very well balanced aggressive stance. There are some visual differentiators both exterior and interior, the M Motorsport 18 inch wheels, which are very pretty where launched on this car and eventually offered as an accessory later in for the e90 range albeit without the M-Motorsport lettering seen on the 320si. Otherwise, the mirrors remained in gloss black regardless of the exterior body colour and from the rear, the single exhaust exit and model designation discreetly indicated that this was a special model. 

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On the inside, special sports fabric was offered as standard equipment, with optional leather which we don’t believe suited the car particularly was offered at a cost, which no doubt helped sell these cars at the time. The starter button has the model designation discreetly etched on the bezel but otherwise, apart from the sporty dark headlining and the tachometer showing a higher rev range, very little difference to a normal M sport 3 series.


It is under the bonnet where this car is completely unique, featuring the hand-built N45B20S engine which was homologated to run in the 2006 WTCC. The engine is combined with a new cylinder head which was supposedly cast alongside the BMW F1 engine blocks at the time in Landshut, Germany. The cylinder bore is increased and stroke decreased giving almost square race ideal ratios. Bigger valves, aluminium cylinder liners and a higher compression ratio combined with the elimination of the Valvetronic system permitting higher revs complete the internals of race purpose characterful engine. Improved cooling is provided by a larger radiator, normally used on 6 cylinder models. The engine is finished off with a striking carbon fibre cam cover which is wonderful to see in such a car. Not only does it look great, it saves 10kg in weight and lowers the centre of gravity at the front of the car significantly.  In other areas of the car, changes include a shorter final drive, larger brakes combined with the wonderful M sport suspension set up.

The engine power is up 23 horsepower from 150 PS to 173 PS but what defines this engine is its racy nature, revving to 7,300 rpm which means it needs to be driven hard to be rewarding, and the exhaust note is surprisingly characterful, giving a lovely 4-cylinder raucous note when revved. However, torque low down is lacking although it does give the car more of a racy feel, even if a little challenging in traffic situations.


Driving this car is a real pleasure for those who enjoy a car with a very characterful engine which needs to be revved but which is relatively underpowered compared to the chassis which is really capable of much more. With the lower weight and centre of gravity coupled with the engine being mounted further back in the engine bay reducing the polar moment of inertia, the car has a handling and balance could be regarded as better than the M3 of the same generation. Hugely rewarding to drive hard especially on a wonderful flat twisty road, despite not exactly what we would consider fast.

Negative points are that apart from the slightly disappointing straightline performance, the car’s engine was clearly never developed with the same level of road car engine life expectancy and durability. The aluminium cylinder liners are the weak point with many suffering from cracks. This can be avoided if treated with care, having the car regularly serviced car and especially warming the engine up before using the revs will help, but there are many cars available with replaced or repaired engines. Some of the cars with broken engines are advertised extremely cheaply because the costs of repair are quite prohibitive with regards to the value of these cars, so many are snapped up by teams or privateers who are still running the original 320si race cars for engine parts. Apart from that, relative to the cars performance, the fuel consumption is far from the manufacturers declared figures, partly due to the valvetronic being eliminated for this model.

In summary, for the price and value, this is a characterful little car with a rather unique reason for existing. It remains useable and discreet with only some few very informed enthusiasts able to identify it. Our one recently sold very quickly; we hope to see another one again soon. Will this car’s pedigree ever be reflected in their values on the market, we are not sure. It certainly will not depreciate but perhaps a little bit too niche to follow in the footsteps of other highly coveted BMWs…. But you never know.


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