If you were to compile a list of things the C63 AMG is short of compared with the BMW M3, I doubt power and torque would be on it. While the M3 makes do with a piffling 4-litre V8, the C63 has AMG’s 6.2-litre V8 squeezed beneath its bonnet. In stock trim this XXL engine makes 451bhp, which is only 37bhp more than the BMW, but there’s the not inconsiderable benefit of 442lb ft of torque, which is a massive 147lb ft more.

Only Andy Green could drive the C63 and declare it rather lacking in the grunt department, so perhaps while Bloodhound is being built he’s freelancing at Mercedes-Benz World at Brooklands, because the team down there has concocted this limited-edition version of the C63 with 513bhp and 479lb ft… 

It’s called the C-class DR520 and just 20 will be built, exclusively for the UK market. Given that, you’d think they might have used good old-fashioned bhp rather than the engine’s PS rating in the car’s name. Then again, I guess DR513 sounds like a camera, or an EU directive. And if you’re puzzling over what ‘DR’ stands for (as we were) it’s Dyno Rated. What an odd choice of moniker.

To be honest, DR500 would get the message across, and that much power would get the job done too, but then the engine upgrade would be too close to that offered by the AMG Performance Pack (481bhp). Other elements of the Pack are used, including the firmer springs and dampers, the limited-slip differential and, thankfully, the bigger brakes. 

You can have the DR in saloon or estate form, and with a matt black or ‘Calcite’ white wrap, which is an appropriate description as it has a chalky feel. I’d go for the black because when the vinyl finally comes off I’d rather have an anthracite coloured C63 than a white one. Both come with black wheels and de-chromed trim, and the saloon gets a blade-like boot spoiler in carbonfibre. Inside there are very deeply sculpted leather and Alcantara seats with red double stitching, matching the Alcantara-trimmed facia, and rather less tasteful ‘DR520’ logos, matching the floor mats. These are contrasted by proper, classy chrome and red ‘DR520’ badges on the front wings.  

Not surprisingly, the engine dominates the driving experience. As usual, it’s hooked up to the AMG Speedshift seven-speed auto, and if ever a car had a surplus of cogs, this is it. Pick-up is superb, whatever the gear, whatever the revs, and this is a vocally expressive engine too, a V8 that’s made in Germany but has an American heartbeat. It cruises with a gorgeous, loping, off-beat rumble and thumps the little C-class up the road with a roar that’s never truly raw but is full of menace. What guarantees terror, for passengers at least, is that the holler is coupled with acceleration so strong you occasionally fear that the floorpan might get kinked. 

That’s in ideal circumstances, on straight, warm, dry asphalt. Mostly the ESP stability and traction control system steps in and muzzles the V8 before it’s got into its stride. Higher up the speed range, when the torque has less chance of unsticking the rear tyres, the V8 still feels mighty and the speed with which you arrive at corners makes even the Performance Pack brakes feel heavily burdened. Same goes for the tyres. The stock rims are five-spoke 18s with 235/45 rubber up front and 255/35 astern, but this car has the optional 19s which have the same width of tyre but an aspect ratio lower. At times other than under power, you hanker after a little more bite, just as you do in the stock C63, it’s just that those times occur more frequently in the DR520. 

What’s pleasing if you’ve just stepped out of a current M3 is to discover that the steering of this C-class is better; there’s a clarity and directness that’s almost Aston V8 Vantage-like. Crucially, the weight and the rate are spot-on, too, which is handy because if you venture to discover what this 513bhp C-class does without electronic intervention, you’ll find yourself busy with the chunky little wheel. 

A short press of the ESP button sets the system to ‘sport’, which slackens the slip control, but only far enough for the rear to give you a good idea how things might escalate if you’re brave enough to give the ESP button a longer press. If you were on a trackday, or driving in the wet, you might choose ESP-Sport for speed and security. ESP-off is what it says (not always the case in other cars) and unshackles the V8 entirely. The gearbox can feel a bit soft in its responses, so for the fullest control it’s best to switch it to M for manual; occasionally straining against the rev-limiter is generally better than having the gearbox upshift mid-manoeuvre…

There is decent mechanical traction with the aid of the limited-slip diff, it’s just that there’s so much lovely, stump-pulling torque it’s easily overwhelmed. Yet thanks to the clear steering and supple, composed ride, you can confidently tweak the DR520’s tail in all sorts of ways: slight over-speed slip in long corners on a steady throttle; stab-and-jab kicks with abrupt throttle and steering inputs in acute turns; big, ballsy drifts that leave thick liquorice-black stripes on the road (once the smoke has cleared). You have options everywhere, and those deep-bolstered seats hold you firmly but softly in place. 

There’s a more direct feel to the M3’s dual-clutch transmission but you can work around the Merc’s more elastic take-up with such enormous, generously spread urge. And this re-worked 6.2-litre V8 makes the BMW’s 4-litre feel like an original Honda VTEC – powerful, yes, but only tyre-troublingly grunty once the tacho needle has passed the 6000rpm mark. Where’s the fun in that?

The performance of the DR520 is probably just off the scale of what even the AMG Performance Pack suspension and brakes were designed to work with, and certainly what the rear tyres were dimensioned to cope with. Also, the regular C63 AMG has a good measure of the DR’s character, so you have to ask if it’s worth stretching to over £62K – an extra £10K – for the DR. And the answer would be ‘damn right!’ I’ll have a black one, please.