Road Test: Mercedes-Benz E Class E63 4dr Auto Bi-Turbo

You might be aware that a new BMW M5 has arrived. And, if you're not, you should be. Mercedes is, and - clearly spooked by the thought of a twin-turbo 552bhp M Power super saloon - has made sure the E63 has some extra firepower of its own. In a way, this is bad news...

Because it means one of the last bastions of European musclecar-dom - AMG's 6.2-litre V8 - has another nail in its coffin. It disappears from the E63, replaced by the next-generation twin-turbo 5.5-litre. At first glance, it's hard to see the benefits the new mill brings. It's not any more powerful (both old and new develop 517bhp), and although torque climbs from 464lb ft to 516lb ft, the 0-60mph time only drops by 0.2secs.

You may have noticed these figures don't tally with those in the spec panel. That's because the car we drove featured the new £6,495 AMG Performance Pack, which boosts turbo pressure from 1.0 to 1.3 bar and delivers more power and speed. But surely that's by-the-by anyway, because the chief pleasure of the old 6.2 was listening to it, and we all know that turbo engines don't sound as good as those that are allowed to breathe naturally.

Only no one seems to have told AMG about this unwritten rule. There's still a lot of swept volume at work here, so the V8 still bellows at start-up and bellows most heartily across the rev range. I really don't think the M5 will sound this good.

And it may well not be as conk-smackingly rapid, either. One big advantage of the new engine is that it delivers its thump over such a wide range. The whole range. As an express engine, it's incredible: 1,500rpm, 2,000rpm, and it's gone.

Another advantage - in fact, the chief one from Merc's POV - is that fuel economy jumps from 22.4mpg to 28.8 and CO2 drops by 65g/km. Those are massive improvements, more than offsetting the modest £1,230 price rise - which incidentally includes £2,500 of extra kit over the old E63.

And it drives so damn well - I reckon Merc realises that this, not the CLS 63, is the car that has to face the M5, and so has spent extra time and effort getting this one right. It's made a difference. The new E63 drives with determination.

Do some switch-fiddling to get the suspension, gearbox, etc, how you want them, and then drive up a tricky road. Feel how keen the nose is, how responsive and punchy the engine, how tightly controlled the chassis, how, while being more accomplished, it still knows how to have fun. If the M5 puts a foot wrong come November, the E63 will punish it.