BMW’s M division is back in the business of building specialty street legal race cars with a new lightweight version of the M3 called the GTS.
The lightweight coupe, due to go on sale in the UK in early 2010 for 115,000 euro (£102,000), has been conceived as a limited edition model primarily for club based racing in much the same way Porsche produces the 911 GT3 Clubsport.
But in a clear effort to link its track based activities with the production car side of its business, BMW’s M division is offering the new car with an homologation package that will allow potential customers to register the M3 GTS for street use.
Helping to distinguish the new track orientated M3 from the standard versions of the iconic two door is a body kit based on that used on BMW’s 320si race car campaigned in the WTCC (World Touring Car Championship).
It includes a deeper front air dam with an integral splitter element as well as a sizeable adjustable boot lid mounted rear wing. The traditional kidney grille and air vents within the front fenders also come in a dark finish.
BMW M division engineers have also given the M3 GTS a carbon fibre roof and dispensed with much of the sound proofing material within the bodyshell as part of a weight saving initiative aimed at raising performance. The new car is claimed to weight no more than 1500kg – some 155kg less than its standard sibling.
Inside, there’s a spartan interior which dispenses with many of the M3’s usual luxuries. The standard trim is replaced by simple carbon fibre and alcantara panels while hard shell front seats, six point harnesses, roll cage and fire extinguisher all form part of the race grade package. Customers will also be able to specify the new BMW with a basic sound system and air conditioning unit.
At the heart of the M3 GTS is a heavily revised version of the M3’s 4.0-litre V8 engine. It has been increased in capacity by 10 per cent, with longer stroke extending the 90-degree unit out to 4.4-litres as part of efforts to provide the GTS with increased low end performance while retaining the strong top end attributes for which the standard engine is renowned.
Other changes include a larger carbon fibre inlet manifold, reworked throttle body butterflies, cast aluminium pistons, a stiffer crankcase and revisions to the sump to provide more reliable oil scavenging at high cornering speeds.
No specific output has been revealed but peak power is claimed to have increased by around 30bhp over the standard M3, taking it up to 450bhp and providing the M3 GTS with a power to weight ratio of 300bhp/tonne.
The increased under bonnet reserves are channeled through a beefed up version of BMW M Division’s seven speed DKG (double clutch gearbox) Drivelogic transmission boating remote shift paddles like those found on the standard M3.
The Getrag engineered unit has been modified with ratios unique to the GTS, more resilient clutch plates and altered software mapping – all aimed at reducing shift times and providing an even more aggressive action in manual mode.
The M3’s electronic M differential has also been tweaked for greater lock up on overrun, while the DSC (dynamic stability control) receives revised software mapping designed specifically for competition use.
Underneath, the M3’s aluminum intensive MacPherson strut (front) and multi-link (rear) suspension has been heavily revised with altered geometry and a rear sub-frame that bolts directly to the body.
The dampers have also been reworked with adjustment threads allowing adjustment of the compression and rebound characteristics. Unsprung masses have also been reduced through the adoption of new 19-inch cast aluminium competition wheels shod with 255/35 ZR 19 (front) and 285/30 ZR 19 (rear) Pirelli P-Zero Corsa tyres.
Changes to the brakes see the single piston floating caliper units used on the standard M3 replaced by new fixed calipers with six pistons up front and four pistons at the rear.