Aren't cars generally supposed to be small, clean and cheap nowadays? How about something ridiculously fast, unnecessarily big and eye wateringly expensive then? Twice.

Yes please. Militant environmental sympathisers prepare your demonstration placards now, because the first proper M-power SUVs from BMW have been unveiled (M as in performance versions, not to be confused with the M Sport trim level) and they're absolutely insane. The X5 M and X6 M are the first 4x4s BMW's M Division has fettled and both are powered by the same twin turbocharged 4.4-litre V8 pumping out 547bhp and 501lb.ft of torque. It's that latter figure that's really important - despite the former making these the most powerful SUVs ever produced - because peak torque comes in at just 1,500rpm and hangs around all the way to 5,650rpm. That means day-to-day stuff like the 50-70mph time and in-gear response should be mind blowing.

As is the fact that they both weigh 2,380kg, but can still sprint from 0-62mph in 4.7 seconds - 0.4 seconds faster than the current king of bonkers SUVs, the Porsche Cayenne Turbo. BMW promises the pair aren't just good in a straight line, though, and has endowed the X5 M and X6 M with a comprehensive dynamic overhaul including adjustable speed sensitive steering, adjustable damping and a six-speed gearbox with three settings. They're all controllable via an 'M Drive menu' integrated into the next-generation iDrive. They get launch control too, and if you're a little unsure about the lowly 155mph top speed, the optional M Driver package will raise that to 171mph - the same as the Cayenne Turbo's, un-coincidentally. Oh, and BMW assures us it's capable of massive four-wheel drifts. We can't wait to try that.

The yearly VED bill for one of these will be a bit of a dread, though, because with 325g/km of CO₂ they're well into the top whack band G - good for a £400 per year charge. That said, 20.3mpg economy isn't too bad considering the performance and weight stats - it scrapes into the twenties because of EfficientDynamics measures like brake energy regeneration.

Inside and out there is, of course, a fairly comprehensive M overhaul, including extra venting for the brakes and engine, and less black plastic on the body, while inside there's a set of tasty leather sports seats, a leather steering wheel and more M badges. The cost? We're not told yet, but when it comes to the UK in October 2009 after its Shanghai Auto Show debut, don't expect it to be any less than £75,000.