In the days of the 'Gentleman Racer', motorsports enthusiasts would drive to the circuit in their Bugatti, Bentley or Aston Martin road car, unbolt the spare wheel and windscreen, race it and then drive home again - and, in fact, cash-strapped Production Class motorcycle racers were still doing just that as late as the 1970's.

But now German tuning haus G-Power has taken that concept to a whole new level, with a radically modified BMW M3 coupé that not only complies with FIA regulations for the GT2 racing class, but is also street-legal even by stringent German standards.

Think about that for a moment: You could legally drive the G-Power M3 GT2 R to Spa or Hockenheim or even Monza, run it in a World championship sports-car race and then drive it home again.

Not only that, the GT2 R is a serious contender in this ultra-competitive class, weighing in at less than 1500kg ready to go, and with 516kW at 5900rpm and 700Nm at 5900rpm on tap, thanks to an SK III 'Sporty Drive' supercharger kit, that'll launch it to 100km/h off the grid in 3.7 seconds, to 200km/h in 9.5 and on to a terminal velocity of more than 330km/h.

'STROKER' CRANK

The SK III set-up has earned its spurs in G-Power conversions for BMW's V10 M5 and M6 engines - and the current M3's four-litre E9x V8 is basically a shortened version of the V10, so G-Power was able to use the special forged pistons and con rods developed by Mahle for its record-setting, 590kW M5 Hurricane RR, together with a modified 'stroker' crankshaft that stretches the capacity of the GT2 R to 4.6 litres.

That's fed by a belt-driven ASA T1-724 supercharger, set for a maximum 0.7 bar of boost, to the BMW V8's individual throttle butterflies through a special airbox, while custom-made oil, water and intercooling systems help it keep its cool.

TITANIUM AUSPUFF

A titanium exhaust system made specially for this car with free-flowing 100 cpsi metallic catalytic converters keeps back-pressure to a minimum and noise within EU roadworthy limits - albeit not both at the same time, we suspect!

G-Power also puts the standard M3 on a diet, ripping out the rear seat and replacing the front apron, all four wings and the rear diffuser with carbon-fibre components, while adding a front splitter and rear spoiler, also made of the light stuff.

The carbon-fibre bonnet moulding has been specially developed to channel the considerable heat developed by the GT2-spec V8 out of the engine bay as efficiently as possible, to prevent the ECU from retarding the ignition (and reducing power output) when a given temperature limit is reached.

RUNNING GEAR

The M3 GT2 R is fitted with G-Power Clubsport coil-over suspension and 20” Silverstone RS forged ruims shod with 245/30 front and 315/25 rear Michelin Pilot Cup rubber.

Braking is entrusted to G-Power ceramic brakes with six-piston callipers in front on 396mm discs and four-piston rear callipers on 380mm platters.

Inside, the standard seats make way for carbon-fibre racing buckets and, just like that another 24kg is jettisoned. The interior is trimmed using a mix of leather and alcantara fake suede in G-Power's signature orange with blue contrast stitching, and an FIA-compliant roll cage ensures that the M3 GT3 R will pass scrutineering (or 'technical inspection' in eurospeak).

HOW MUCH DOES IT COST?

Plenty.

The supercharger kit and titanium auspuff will cost you €41 650 (R535 000) not including installation fees, and the carbon-fibre body kit is €30 000 (R385 000), with the special carbon-fibre bonnet an extra €3600 (R46 000).

The rims and tyres will stand you in at €12 000 (R154 000), while the ceramic brakes will flatten your wallet to the tune of €14 460 (R185 000) for the front wheels and €11 778 (R151 000) for the rear wheels.

Alternatively, for €195 310 (R2.5 million) ex works, G-Power will source a standard M3 and build you a complete GT2 R.