As with all the top AMG models, the CL65 comes as standard with a speed limiter that restricts it to 155mph, which you have to admit is a bit of a shame when you've got 612bhp and 738lb ft of torque at your disposal. But the company offers the option of de-restricting the car, which is decent of them. The work can only be carried out at the AMG factory - which is why we're here, and why I'm happy to let the engineers tinker with the CL65 for a few more minutes.
Unleashing the full potential of the CL's mighty twin-turbo V12 sounds terribly dramatic, but in reality the process simply involves 'flashing', or re-writing the car's ECU software. It's the safety checks required before the car is let out of the factory that take the time: AMG ensures the correct Michelin tyres are fitted and correctly inflated, and also double-checks components such as brakes and suspension arms, even though this is a new car.
While the electronic surgery is taking place, I pop up to the engine shop to meet Uwe Gruber, one of a team of six that hand-builds the engines for the CL65 and the up-coming SL65 (the SLR engine is also built here, but on a separate line). Uwe builds an engine a day, and is responsible for the engine in our car.
He shows me the dyno hall where each completed engine is subjected to a two-hour check to ensure all is well and that it's producing the requisite amount of power. It's while I'm watching an engine's exhaust and turbos glowing cherry-red on the dyno that I get the nod that our car is ready, with just an AMG sticker inside the fuel filler cap denoting that this car has been de-limited. Almost time to head off...
Oh I love jobs like this: a proper blat across Europe in an over-powered German limo. And I've been looking forward to reacquainting myself with the CL65; I drove it at launch in Monaco last year (evo 061) and it didn't live up to its on-paper promise, though on that occasion its performance potential was rather hampered by over-crowded roads. This time things should be very different. Storming the unrestricted German autobahn network in a de-limited CL65 sounds like much more fun than being stuck in a French traffic jam. To make things even more interesting, we're planning to leave it quite late before we set off; travelling through the night, we'll really be able to give the CL65 its head.
The pace of change at AMG is almost as amazing as the speed of the cars it produces. The last time I visited, just a few years ago, there was only a small showroom, with the workshop just up the road producing bespoke limited-edition cars like the original E55. Now it's turning out more than 24,000 cars a year. That's an amazing turnaround and it stemmed from when supercharged engines arrived in the C32 and SLK32 models. Both sold double the number AMG expected. But the biggest sales shock was to follow when the SL55 was launched. It continues to sell at three times the expected volume.
It seems that AMG customers can't get enough of this combination of luxury and supercar performance, and the CL65 is the ultimate expression of the AMG philosophy with its insane 612bhp and 738lb ft of torque (the engine is actually capable of producing 885lb ft, but it's capped because the current gearbox can't cope with more).
Point a regular CL65 at an empty autobahn and it'll tear up to its electronically-limited 155mph top speed from a standstill in a g-fest lasting around 20 seconds before the engine's standard ECU puts the kibosh on it and stops the sparks. That must make it pretty galling when someone you've just blown away in a 911 boasting only half the horsepower then sails past your stricken CL65. Ordering this car without the speed limiter being tweaked is a bit like ordering the latest superbike with a set of stabilisers.
Time to go. The guys at AMG know the autobahn network in intimate detail and help us plan our route through Germany on as many de-restricted roads as possible. Helpfully, the A61 is right next-door to the plant and takes us north, more or less in the direction we need to go. Perfect.
As we pull onto the A61 for the first time it's around 6pm and the early-evening rush hour is in full swing, yet there are enough gaps in the traffic to give the CL65 a quick squirt and get a feel for what it's going to be like on the journey ahead. You won't be surprised to learn it feels shockingly, almost disorientingly quick, with a surreal dose of acceleration from 100 to 140mph that doesn't let up much even after that (later we hand-time 100-120mph in 2.9sec and 120-140 in 4.8sec). The car simply romps past the old limit of 155mph; photographer Gus Gregory tells me the speedo has already registered close to 180mph on a couple of occasions and we haven't even seen a properly clear stretch of autobahn yet.
Jeez, these are serious speeds for a big car, but the CL65 seems to be in its element. I've got a superb view from the supremely comfortable driver's seat, sitting much higher than you would in any conventional supercar, there's barely any wind noise thanks to the double-glazed windows, and the twin-turbo V12 is just gently grumbling to itself. It feels completely unstressed.
The only thing that's gone slightly awry is the ride. CLs have always seemed to make a bit of a meal of small ripples in the road surface but this car seems particularly bad, possibly because the tyre pressures have been increased; surface joints in the concrete set off an unseemly judder through the car as though it's under-damped or there's a looseness in the body.
The V12 is swilling fuel at a serious rate, the 11mpg average forcing a stop to refuel after 170 miles, or every 80 minutes or so. On the bright side, the crawling trucks that were hampering our progress are fast disappearing, camping out for the night in the truck stops littered along the roadside. Then, as we head towards Bonn, we finally luck across a deserted stretch of autobahn - the first chance we've really had to max it.
I thump the throttle into the carpet, the CL65 piles on speed beyond 150mph as if it weighs the same as an Elise, the mighty, mighty torque neutralising any drag experienced by the huge body scything through the cooling night air until: buff... It butts into a new limiter set at 186mph and suddenly stops accelerating. You can feel the mighty engine gently stuttering, but no matter what you do it just will not go any faster.
It seems that Mercedes' view of de-limiting isn't exactly the same as my understanding of the word. What it actually means by de-limiting is moving the electronic barrier up from 155mph to 186mph, and the reason is that this is the safe limit for prolonged running with these tyres. It's hard to argue with that, and, let's face it, 186mph is still pretty damn fast in a big four-seater coupe. Pretty damn fast in anything...
The autobahn is practically deserted now, and we time just how long the 65 takes to go from the old limit of 155mph to the new limit of 186mph. The answer is seventeen delirious seconds.
The de-limiting costs £1700, which works out at £55 for every extra mile per hour gained. I reckon that's excellent value. It gives you another seventeen seconds at full power to experience the 'woooooah' factor as that mighty engine takes hold and flings you down the road. Seventeen extra seconds to relish the precise meaning of torque, the exhilarating feeling of you alone controlling such enormous power - endless, seamless power thumping you into the horizon probably like nothing you've experienced before. It's all rather hypnotic, almost eerie in the way the car wraps it all up in several layers of luxury and makes it appear so easy.
But there's something else in those seventeen seconds that's every bit as awe-inspiring as the solid push in the back. As the speedo needle powers round, past the 160mph marker and on a collision course for the 180mph mark, there's a momentary slowing of the acceleration as the gearbox slips out of fourth and into fifth before the power takes hold again. It's a magical moment, reinforcing the aura of utter effortlessness this car radiates so strongly to its occupants, and it's a moment that only occupants of de-limited CL65s will ever experience.
Something else they will never get the chance to experience is the sensation of braking hard from 180mph; and that's pretty amazing too. With a clear road all around I begin to brake, the nose starts to dip and I squeeze the pedal harder still. Flotsam from around the cabin starts to fling itself towards the front of the car, Gus and I look at each other and start to giggle as our bodies get relentlessly pushed into the seat belts - we're hanging in here against our will. From 180mph you get plenty of time to take it all in as the eight-pot callipers torture the 390mm front discs until I give in at around 80mph and relax the brake pressure.
Phew, that almost hurt, and in the mirror I can see something I've never actually seen before: two long, grey lines of rubber etched into the concrete autobahn from where the tyres have torn at the road surface. This is a very serious car.
We're closing fast on the border with Belgium and the disturbing thought of its 74mph speed limits. There's a last hurrah as we charge the final few kilometres on the German autobahn at close to the 186mph maximum before reality has to take hold. Except it doesn't; 112mph is about the best I can manage on this arrow-straight motorway that heads directly towards Bruxelles.
We're not alone; the rest of the traffic seems to be ignoring the draconian limit as well, and soon we're around the city and setting our sights on the coast-bound motorway towards Ostende. The CL65's superb seats make it all utterly painless. If only all travel could be like this.
The road signs start to include Calais but, just as we're busy congratulating ourselves on evading the law, a Belgian police car storms out of a lay-by and into our wake. Luckily, I spotted him as he tore down the slip-road and after we spend the next 20km abiding by the 74mph limit - cruise control can be a very handy thing - he gives up on the idea of emptying my bank account and heads off for a coffee in a service station. That's the cue to massage the throttle and get the CL back up to a comfortable 110mph cruise as we devour the last few miles into France.
There's a bit of a wait at the Eurotunnel terminal in Calais (at this time of night the trains only run once an hour) so we fill up with some coffee and sandwiches before driving onto the train that will deposit us in the UK at an unseemly 3:30am.
It's just before 5am as I finally roll up my drive in the Cotswolds. We've covered 900 miles and passed through four countries since leaving AMG around 12 hours ago, and at least two hours of that were taken up with photography.
The car has behaved impeccably. Journeys like this are exactly what it's been made for, although the further away from the German autobahn you are the less sense this car seems to make. But then I guess a Caterham or a GT3 RS makes less sense the further you take them away from a racetrack. It's a huge achievement by AMG to make a car with this much power so incredibly civilised and pleasurable to drive. I can only begin to imagine what it's going to feel like once they find a gearbox to cope with the full 885lb ft of torque...
