Over the years I’ve driven all sorts of dangerous cars, including a racing machine with no front brakes and an engine from an aeroplane, but until yesterday I hadn’t driven anything quite as deadly as this new Mercedes-Benz CL 63 AMG.

If you happen to be reading this in a Mercedes-Benz showroom, about to part with £103,540 for one and you want to retain possession of your driving licence, my strong advice is that you put down your coffee and head for the exit rapidly.

Usually I have no time for people who suddenly notice they’re driving much faster than they thought, but this CL’s ability to accrue speed by stealth is remarkable. And while it is clearly part of a wider arms race by manufacturers to produce ever more powerful cars (the 518bhp V8 motor is the most powerful of its type in the world), the blame for the frightening numbers that appear on its speedo is ultimately yours. The quality that will earn you what Americans quaintly call “fast driving awards” until you run out of points is the deadly cocktail of power, the ease with which it is delivered and the almost total absence of any of the usual sensations of speed.

Accelerate hard and the 6.2 litre engine (I have yet to fathom why Mercedes calls it a 63) makes all the barrel-chested V8 rumbles you could hope for, but settle into what you think is a steady cruise and it falls near enough silent. There’s negligible wind noise, despite the fact that, in line with Mercedes coupé tradition, it has no B-pillars, and even road roar on vast (optional) 20in rims is well muted.

The ride quality is exceptional, so you just sit there cocooned from reality at what seems like a modest canter until you squint at the tiny numbers on the ugly AMG speedo and realise the disparity between the speed you are doing and that you thought you were doing is the difference between the law not raising an eyebrow and having to talk your way out of a ban in court.

Clearly Mercedes is aware of this: know which buttons to press and you can summon up an enlarged digital speed readout on the dash. You can, of course, simply set the cruise control, though the active system in the car I drove has the disconcerting effect of keeping you so far from the car in front it’s a speck in the distance. As an ultimate failsafe, Mercedes fits a programmable speed limiter that lets the driver select a speed it will not exceed under any circumstances.

It is, of course, a car born for German businessmen used to bludgeoning their way down the autobahn with their lights on full beam, indicator permanently on and the speedo as close to the electronically limited 155mph top speed as humanly possible. Within the crowded confines of the British road network, it feels as confined and far from its natural habitat as King Kong in New York.

But while it may not be suited to this compromised environment, that is not to say it is entirely unable to impress. The thunderous power of its engine is something not to be forgotten, even if the seven-speed automatic gearbox to which it’s tied is sometimes slow and hesitant. And should you find an example of that increasingly rare commodity, a quiet, open and winding road, you will marvel at the precision and control the AMG engineers have brought to a car that, lest we forget, weighs more than two tons and is based on the vast S-class saloon. It’ll go round corners at speeds you’d not credit, knock the air from your lungs when you brake and thread itself down a narrow lane like a car two sizes smaller.

Indeed, in all ways that are easy to measure, it would appear superior to the Bentley Continental GT, the car it was put on earth to beat. It has a little less power but a whole lot less weight, so is comfortably quicker. I don’t doubt it has superior ride and handling qualities, and while the Bentley is cramped in the back the CL is a comfortable four seater, and its boot is vast.

All it lacks is perhaps the most important thing of all to most customers looking to spend more than £100,000 on a coupé. They don’t want true luxury because, if they did, they’d have bought a limousine; nor do they want some ultimate driving experience because then they’d have bought a supercar. What they’re after is a sense of occasion, a feeling of anticipation when you see it on your drive, of pride when your friends see you in it.

Bluntly, the Bentley has that in spades and, for all its many talents, this Merc does not. Its cabin is insufficiently special in feel and look, its exterior attractive but ultimately not that memorable.

Forced to choose, I’d have the Mercedes because it is the more capable car, but then I’m not a typical customer. The idea of a car this fast and capable may be hugely appealing, but the reality on our clogged and camera-loaded roads is less so. Technically the CL 63 AMG is a fine achievement, but the truth is it needs more space than we have for it to shine.

Vital statistics

Model Mercedes-Benz CL 63 AMG

Engine type 6208cc, eight cylinders

Power/Torque 518bhp @ 6800rpm /464 lb ft @ 5200rpm

Transmission Seven-speed automatic

Fuel/CO2 19mpg (combined) / 355g/km

Performance 0-62mph: 4.6sec / Top speed: 155mph (limited)

Price £103,540

Verdict Right car, wrong location

Rating 4/5

Date of release Available now

The opposition

Model Bentley Continental GT £117,500

For Presence, build quality, badge, performance

Against Footballing image, ride quality, cramped in back

Model Aston Martin DB9 £109,750

For Looks and sounds terrific, beautiful interior, name

Against Small cabin, illegible instruments, tiny boot