There's only one thing that irritates about the new CLS63 AMG, and that's its name. I'm sure there's a solidly Germanic reason for it somewhere in the corridors of power at Mercedes HQ, but, after years of reliably indicating the size of the engine, they are now just a lie. So instead of getting a 6.3-litre lump, as the badge brags, we now get a 5.5-litre instead. What happened? Did someone make a job lot of badges which have to be used up? Or did Hans in the engine dept suddenly and unexpectedly throw down his wurst last week and decide that all of AMG's big V8s would immediately be 800cc smaller and use twin turbos?Whatever - and I know BMW is doing the same thing - it's not a big issue, but it does highlight just how problem-free the rest of the new CLS AMG is when all you have to kvetch about is its name. And the best way to avoid that is to get in and drive the thing as far and as fast as possible. Apart from having your every action monitored, checked and occasionally curbed by the Tronic army, chances are you will also emerge feeling like you could and would want to do the drive all over again. The CLS AMG empowers, cossets, connects and excites in so many ways, it genuinely makes you wonder if you would ever need any more car than this. Maybe need is the wrong word. Few people could actually need anything other than the base model, which is still festooned with more tech than a teenager's bedroom, and more luxury than a Chanel counter. Want is probably a better way to describe it. And there's plenty of that going on in the CLS AMG, starting with that size-four engine with the size-six name.Known inside AMG as the M 157, this military grade, twin-turbocharged V8 produces an unrelenting 518bhp and 516lb ft (that's 11bhp and 51lbft more than the outgoing 6.3 normally aspirated unit) thanks to some careful juggling of the fuel and air mixture. Spray-guided direct injection, piezo injectors and variable camshafts optimise the engine's digestion. Air-to-water charge cooling stops it from grenading. And generator management - it only cuts in when necessary, rather than just sapping power by being constantly in the loop - plus a stop/start system prevent it from downing the entire tank before you can get to the next petrol station or spin the tyres through to the canvas. Mercedes claims the 157 drinks a third less than the AMG 6.3, which sounds like madness. But we'll leave that for now. However, the company also claims that 157s fitted with the optional AMG Performance Package drink exactly the same amount of fuel despite offering another 32bhp and 74lb ft - plus an 187mph top speed, instead of the 155mph of the cooking version. A piece of mechanical (and statistical) magic that is caused by upping the max charge of the turbos from 14.5psi to 18.8psi. You can tell which CLSs have this package installed in two ways\: the carbon-fibre engine cover and red brake calipers, if the car is standing still, and the angry metallic grey blur with a carbon rear spoiler that passes you, if it's moving.The other key contributor to this new-found health and efficiency is the AMG Speedshift seven-speed transmission, which is also quite the box of tricks. Instead of using a power-and fuel-sapping torque-converter to slur from one gear to the next, or borrowing the SLS's dual-clutch system (because it's designed for the gullwing's higher-revving, lower-torque engine) the Speedshift uses a wet start-up clutch. The 'box has four modes, one of which is there to keep the eco-legislators happy (and deliver those insanely low fuel consumption figures), three which are there to do the same for the driver. In Controlled Efficiency, or C, the engine sighs and dies as soon as you come to a stop, and the gears change with all the urgency of a vintage jukebox. It all gets much more interesting in Manual, Sport and Sport Plus modes, though. The engine stops playing possum at every junction, and you can get on with enjoying the car.Which really isn't that hard to do. The standard 2011 CLS has already had the benefit of a substantial chassis and body make-over, finding a visual and driving fluency that the E-Class struggles to find. The addition of a unique programmable adaptive suspension system by the AMG crew has made the CLS AMG even better. I had worried that this would turn the ride to concrete, but that's not the case. Yes, the car stays flatter through corners, but not at the expense of your teeth or spine. Likewise the steering has a good amount of feel - much more than you'd expect from a car of this size and weight. The front track is almost an inch wider, but it's mostly down to the careful tuning of the steering from the tyres' contact patches all the way back up to your palms on the Alcantara-clad AMG wheel.A key component of which is the tasty 19-inch titanium painted and polished wheels, which are broad but not excessively so. These help stop the car start picking its own lines when the roads get rough. The 36cm brakes are less modest. We didn't have the opportunity to try to overheat them on a track, but on the road, they felt faultless and fade free. Even so, just in case that's not enough, carbon ceramics are available as extras.So there's very little wrong, and an enormous amount that's right, with the way the new CLS AMG goes about its business. It's very fast, very comfortable, surprisingly fun to drive, looks mean, particularly in the matt paint, and feels like it has the durability of a JCB. The badging will be a nagging issue for OCD freaks, but even that's sortable... delete the badges altogether.