The fastest saloon in the world

It can eat Ferraris, but a souped-up Merc doesn't send Richard Lofthouse into orbit

Given Top Gear presenter Richard Hammond's recent dreadful accident it might be that we're about to undergo a prolonged soul-searching about the worship of speed.

Not so in Germany, where there is still no speed limit on the autobahn and drivers treat the fast lane like a race track. The name of the game is large German saloons, mercilessly driven with full-bore acceleration, followed by full-bore braking in the constant heavy traffic

Nor have the manufacturers lost their passion for speed. Meet the Mercedes-Benz tuner Brabus, and its latest creation: the world's fastest saloon, the Rocket.

Sven Gramm, Brabus's PR boss, took me out on the A31 near Bottrop, the Ruhr valley town where the tuning company was founded in 1977. No sooner did we reach what I thought was terminal velocity at about 100mph (160kph) than he kicked down the automatic transmission, summoned up third gear and smiled as the car tangibly squirmed and the yellow traction control light came on, indicating that the rear wheels were losing grip under the fierce acceleration. All this on a fine, dry September day.

Gramm then accelerated up to an indicated 290kph (180mph) before having to brake heroically to slow down before we came upon Fiat the Flea "Panda" up ahead in the distance, whose 65mph meant that we were gaining on him as though driving at 115mph towards a stationary object.

The experience lacked drama, and didn't feel hair-on-fire dangerous. The Brabus Rocket, based on a two-tonne Mercedes CLS, felt completely unruffled.

"The point is not that the driver will always drive at these speeds but that they will know they have this capacity," says Gramm, "that they are faster than anything this side of a Bugatti Veyron but with none of the fuss - and with four doors and a proper trunk."

The Rocket is a practical rocket in other words, something to bear in mind when blowing €407,000 (£273,000), the price with all bells and whistles.

Where does this crazy budget go? Principally on serious rebuilding of the already mighty Mercedes V12 engine. Brabus bores it out from 6 to 6.3 litres, bolts on two giant turbochargers and makes some serious additions to most of the drivetrain, suspension, wheels and brakes. Then they fit it to a CLS.

The result is a stupendous, parallel universe of statistics: 730bhp; 1,320Nm of torque (electronically limited to 1,100Nm); 0-125mph in 10.5 seconds and the glittering headline stat: a top speed of 225mph, or 362.4kph. So the Rocket really is the fastest four-door saloon in the world.

Brabus also transforms the CLS interior with swathes of expensive, butter soft leather, alcantara head-liner and a gratuitous list of optional extras all costing serious money.

But to be brutally honest, nothing about the Rocket experience was particularly special. It accelerates from 100mph like a Porsche Boxster from a standing-start, but the sound and fury is so well damped that you wouldn't know it. It was very little different from the sort of supercharged musclecars that America has specialised in for years, albeit faster and unfathomably more expensive.

On our return blast I overtook an Audi S8 in the nearside lane, only to realise that he was accelerating flat out too. Now, let's imagine the Audi had been some other brawny contender disguised outwardly by a Loro Piana suit. Say a BMW M5; a Bentley Flying Spur, or a Maserati Quattroporte. Well, they'd all be destroyed by the Rocket too.

There ought to be a new Marvel comic called Tales from the Autobahn for boys who can't sleep. If there was, the Brabus Rocket would be the opening spread, and it would have flames shooting out of its arse.

Yet the disappointing reality is that this is another silver Merc with a melancholy, black interior. Gramm rightly noted, however, that the Brabus is more comfortable and less highly strung than the (slower) Ferrari 612 Scaglietti. How the Rocket goes in corners is harder to say since we didn't tackle any, but considering you could buy three Ferrari F430s for the same money perhaps it's an academic question.