Nardo high-speed test track in sunny southern Italy presents a very special challenge for makers of fast cars. Basically it's a banked circle with a four-kilometre diameter, a 12.3-kilometre ring that functions as an infinitely long straight where you can 'put foot' and drive absolutely flat out until either something breaks or you run out of fuel.
Add uncomfortably high ambient temperatures and it simply doesn't get any more challenging.
Once a year the German petrolhead publication Auto Bild Sportcars hires the Nardo facility and invites manufacturers, tuners and 'special' builders to the ultimate top-speed shoot-out, open to any car that can pass Germany's draconian TUV roadworthy regulations.
Most of the cars, not surprisingly, arrive on trailers, prepped to within an inch of their lives, but the performance junkies at BMW tuning specialist G-Power have always driven their entry the 1500km from the company's base in Autenzell, Bavaria to Nardo to prove that their products really are street-cars, not thinly disguised competition vehicles.
And in 2011 their previous-generation M3, with SK II supercharger system delivering 418kW, did just that - and became the word's fastest street-legal BMW M3 with a GPS-verified top speed of 333.1km/h in the process.
So this year they bolted on a higher-volume SK II CS supercharger and set out to break their own record. Many tuners post top-speed numbers derived from a short blast on a dynamometer in the workshop, but Nardo's abusive real-world conditions stress running gear to its limits, bringing into play factors such as air resistance and tyre creep.
Sadly, a broken part worth just few cents cut short the G-Power M3's top-speed run at 326.2km/h, but the G-Power crew weren't about to let it go at that. Two days after the Auto Bild Sportscars high-performance event and ended the festival had ended they were back at Nardo for another try - and this time Mr Garmin and his friends in the sky confirmed a terminal velocity of 337.6km/h.
See it for yourself on the video below.
To celebrate this new benchmark for the world's fastest street-legal V8 M3, G-Power is building just 30 examples (in honour of the company's 30 years in the go-fast game) of a special version called the Hurricane 337 Edition.
Based on the previous-generation V8 M3, each one has an ASA TI-523 radial supercharger, breathing in through a high-volume intake system with a racing air filter, and cast-alloy intercooler and air-box, and out through an all-titanium exhaust system with free-flow competition-spec catalytic converters that's 27kg lighter than the stock auspuff.
With boost set at a conservative 0.5 bar, it delivers 454kW and 595Nm, while a carbon-fibre aero kit and special Hurricane 337 badging complete the standard conversion.
The silver M3 Coupé in these pictures is actually the first customer car; the owner also specified G3M ClubSport coilover suspension, a G-Power braking system with huge discs - 396mm in front and 380mm at the rear - and 20” Silverstone Diamond alloy rims shod with Michelin Pilot Sport radials.