There's a case for the big CL coupes to be recognised as the most fascinating cars Mercedes-Benz make. Granted, they don't seem the most immediately relevant - especially this CL 63 AMG hot rod, carrying as it does a list price of over £100,000 and expected sales that are modest to say the least. Where the CL is most intriguing is that because of its smaller sales footprint than the S-Class saloon from which it's loosely derived, it can act as the test bed for the latest technological features.

What appears on a CL may or may not eventually filter down to the sorts of C or E Class models many of us can aspire to. Sometimes the technology proves a dead end. At other times it's a revelation. The CL 63 AMG might just have a claim on being - at launch at least - the most thoroughly engineered car on sale.

The 6,208cc V8 engine is no blood and thunder piece of ironmongery. Some previous CL models have resorted to the blunt implement of forced induction to make the headline power figures but this one utilises the world's most powerful naturally-aspirated production V8 to serve up 525 screaming horsepower. Get in and expect the usual CL low end surge and you may come away surprised. This is an engine that demands to be taken by the scruff of the neck and revved, making its peak power at a heady 6,800rpm.

The 7G-Tronic automatic gearbox and clever traction and stability control software makes clean getaways simple, the car punching through 60mph in 4.5 seconds on the way to a limited top speed of 155mph. An optional AMG Drivers' Package removes the limiter and 186mph is then attainable. A day's advanced training at a major European race circuit is also wisely included in the package. A second generation Active Body Control (ABC) system offers flatter cornering and the steering serves up more feel than you would anticipate. The AMG spring struts provide firmer dynamics when the gearbox is switched into Sport/Manual modes. It's amazingly lithe for such a hefty car and the engine's soundtrack at the top end could easily lead you into temptation.

"The CL 63 AMG might just have a claim on being the most thoroughly engineered car on sale"

The aggressive front spoiler, ribbed rear diffuser, tarmac-skimming stance and huge 19-inch AMG alloys instantly mark the CL 63 AMG down as something quite different to the usual CL norm. Where the standard CL models are smooth, relatively low key and ineffably discreet, this AMG model has a lot more front. The interior is beautifully styled with a move away from the confusing spray of buttons that has plagued some Mercedes models. I remember sitting in an SL65AMG and counting over 70 buttons and switches on the dashboard. The CL adopts a wholly cleaner look with many of the functions marshalled by the COMAND control system.

The latest generation CL is more elegant in its proportions than its predecessor, a car that could look awkward from some angles thanks to its sharply tapered C-pillars. While the latest car is less extreme in its styling, it's undeniably handsome. It's also big, expanding in every dimension to add not only gravitas, but also some welcome room in the rear seats and the boot as well. At 5,065mm from stem to stern, it's 75mm longer than the old car as well as 14mm wider and 20mm higher. This is a serious piece of automotive real estate, the range-topping car tipping the scales at 2,085kg. That's 375kg heavier than a BMW M6 so you can excuse it for not playing the track day warrior too convincingly.

The CL range consists of three other models alongside this £103,450 CL 63 AMG. You'll pay a fraction more for the luxury V12 CL 600 and quite a bit less for the entry level V8 CL 500 but the CL 65 AMG is in a league of its own at around £150,000. There's no doubt that the CL 63 AMG is a seriously expensive car but its key rival, the Bentley Continental GT, is a good deal dearer, not as quick off the mark and has become tarnished with a rather Premiership image. Despite this, it was enough to nail down the coffin on the old CL model and together with the Aston Martin DB9, it reduced CL sales to a trickle.

The latest model counters with more attitude and some incredibly smart technology. I could write 1,000 words on how smart the headlights are. Then there's the brilliant adaptive cruise control that can handle the worst the M25 can throw at it without a murmur of complaint, the Advanced Parking Guidance system and the Night View Assist, an infra-red system that transmits images to the instrument panel so the car can literally see in the dark.

Economy isn't stellar. Despite the engine being one of the most efficient units of its type, it's still a 6.2-litre V8. Mercedes proudly proclaim its 19.0mpg combined economy figure and in comparison with similar cars, that's impressive but it still means that a 'real world' figure will likely hover somewhere around 12 or 13mpg. Ouch. Insurance is also hefty, the CL 63 AMG rated at a tip top Group 20. Put bluntly, you'll be hard pressed to find a car this side of genuine exotica that costs more to run.

Still, there are few more genuinely impressive cars for sale than the Mercedes CL 63 AMG. Perhaps part of its charm is that it delivers so much more than anticipated, offering a great engine, a very composed chassis and more 'surprise and delight' functions in the interior than in Willy Wonka's chocolate factory. Yes, it is savagely expensive to run and will probably have its trousers taken down by a MINI Cooper on a typical B-road but get it on home turf and I'm struggling to think of anything I'd rather be in.

There's a completeness, an integrity of engineering, a reassuring feeling that this CL 63 AMG has your back in any given circumstance that's wholly endearing. Some will see it as a profligate irrelevance. Look below the surface and you'll find a car that fulfils its remit as capably as a Porsche 911 or Ford Focus discharge theirs. The bar has been raised again.