If you want a 300 km/h supercoupé for around €150,000, you've got two options: the hardcore BMW M6 or the refined Aston Martin DB9. By MATTHEW ROBINSON and RICHARD LOFTHOUSE

The world of the extreme performance car has never been more confusing than it is right now. Twenty years ago, the exclusive 300 km/h club was the preserve of only the most extreme machinery – vehicles costing the same as a large country home. The 21st century has altered our perceptions, however. When even your most basic hot hatch can knock on the door of 250 km/h, the bar for the super league has been raised.

The BMW M6 and Aston Martin DB9 are two heavyweights that represent the threshold between everyday usability and outright supercar: Ferrari-like performance but without the unwanted attention, wafer-thin clearances and non-existent luggage space.

The BMW M6, launched in 2005, is BMW's flagship. It packs a 507 bhp five-litre V10 engine, capable of propelling the beast to 328 km/h (delimited). Answering for Britain is the simply stunning Aston Martin DB9, the automatic Touchtronic II model (the M6 only comes with the robotised manual seven-speed SMGIII transmission whereas the DB9 can be specified with a traditional six-speed manual). The Aston has an even bigger six-litre V12 engine. It develops just 450 bhp, although it's more flexible – 570 Nm of torque to the M6's 520 Nm.

Both offer similarly ballistic performance but go about it in different ways. The M6 attacks the road, snarling and growling from corner to corner, the ride harsh, the crisp, metallic wail of the engine sending adrenaline levels through the carbon-fibre roof. The Aston, well, it cossets you. It wraps itself around you and soothes you into serene relaxation as it sets about the gruelling business of destroying big distances in minimal time. Two different approaches, one inevitable end-product: ultra-rapid pace. So which to choose?

In terms of aesthetics and sheer prestige, the Aston has the German upstart licked. An Aston Martin will always have higher status than even the best BMW and this is no exception. The Aston may have the higher purchase price, but it'll also hold its value better. And on looks, there's no contest. I think the M6 is a wonderful car to behold, especially in Interlagos Blue, but the Aston is a thing of pure beauty. As much as the muscular BMW appeals, it's the DB9 that draws the longing stares.

The DB9 continues to win points inside, having an interior worthy of a seven-star hotel, replete with supple blue leather, alcantara headliner and cherry wood. Sadly, though, it can be difficult to get a comfy driving position, thanks to a cumbersome transmission tunnel. The BMW? Well, it's all laid out nicely and it's beautifully put together, but there's only a bit of faux carbon fibre trim to differentiate it from the 630i, worth half as much. It's a technological marvel but it doesn't feel like a luxury motor. There are neat touches: the head-up display, which projects speed and gear ratios onto the windscreen in the driver's line of sight, is a marvel and should be standard fit on every car, it works so well. But the magnificent engineering that has so evidently gone into all of the Aston's switchgear leaves