While RS 6 is indeed a hugely powerful, superbly equipped and mesmerising machine, it's also extremely hefty. Which brings its own problems.

The car rides well enough, but we're going to have to disagree with overseas reports that it?s the best of this bunch. You can feel the mass of the machine as it gently pogos front-to-back over challenging surfaces and that makes it feel a trite distant in steering and other response. We?re pulling hairs here, but considering some of the rivals we still have to discuss, that we have to do.

The ride is also quite bumpy but it has to be noted that RS 6 still responds to driver input well and is perfectly predictable and confidence inspiring, it brakes brilliantly and on the road it never gave a hint of trouble in retardation.

It sounds great, if a bit too muted, but that deeply under-toned wild animal howl and growly reaction to auto gearshifts is something to behold. And that autobox is one of the best we have driven ? responsive, intelligent, yet docile when needed.

RS 6's cabin is ageing a little now, but so are its rivals, which leaves it on top of this little pile.

RS 6 is also expensive and to spec it up is also quite hefty on the wallet. And like the other cars on these pages, it?s bound to be a bit of a depreciation disaster.

While on running costs, don't believe for a second that this thing will ever be any better on fuel than either of its already gluttonous rivals here ? it sucks fuel like a sperm whale filters plankton out of seawater ? at a truly frightening rate.

For now we'll leave the Audi and quickly review the others before returning to wrap it up in the way any super saloons should be compared?

As noted up front, the BMW M5 is already a classic. BMW's recent announcement that its M-cars will be force-fed in future has made sure of that, although as regular readers will know, we knew that long ago.

The core of the beast is that 8300rpm 373kW 520Nm V10. Brilliant and brutal, it?s probably the epitome of normally aspirated engines ? in more or less conventional cars for sure. It?s mated to that much maligned SMG II 7-speed trannie, which we agree is horrible in the parking lot. But on the open road and on track in its bareback sporting form, I'm still convinced it?s the best ?box out there.

That?s all rounded off by a device called BMW M Differential that is manna from heaven if you have the credentials to drive it flat out. In typical M form, 80 percent of the M5?s suspension and other components are specifically developed and BMW M even managed to get that Bangle-struck Korean-kitsch 5 styling to look like something worth driving in the M?

On the road, M5 is brilliant. It has eleven SMG settings of which only one matters ? the most violent and in that bareback mode with the full 500 horses harnessed (yes, you have to push a bloody button to get that last hundred to cooperate?) there is very little out there that will ever live with a well-driven M5.

It makes a marvellous noise, swaps cogs with a hammer-shot, possesses steering feel that nothing in this class can come near and follows through with a polished and predictable repertoire of perfectly poised handling and road holding. But I stress again ? you have to be right on top of your driving game before you ever extinguish that traction and dynamic stability control.

M5 is the driver's car of super saloons and it is a tragedy indeed that BMW sees it necessary to see an end to this most pedigreed of super saloons. This one is an icon beyond any shadow of doubt?

M5 boasts a most impressive set of performance figures. Having driven one now for three years I can state with absolute authority, that it matters not how hot or how cold it is, whether the inlet system is too hot or not, or how hard you've been driving it all day ? the only thing that will affect an M5 from producing consistently repetitive performance figures is if you drive it like a fool and light up the tyres by mistake.

Or of course if you run out of fuel or tyres, both of which are quite possible if you drive it like a hoon all day long.

0-100 comes up in the low fives or tall fours all the time - in a 2-3 tenth band - and M5 is totally reliable in returning mid-thirteen quarter miles at just off 180km/h, with the kilometre reeled off at 225-odd in about 25 seconds.

All of which the Audi seems to battle to match as soon as the mercury slips past 25 degrees - which is just about every day in SA ? and after it?s hit traffic once before he found you?

When it comes to cost, it seems a little ludicrous that the M5 costs a bar when you can get such good stock for half that pretty much all around town, but that's something you have to live with if you want the latest and the greatest. And it sucks fuel too, albeit at the rate BMW says it will and it?s pretty consistent at that too ? 20 l/100km in town is constant.

Yes, M5 is flawed. But all of a sudden it doesn't seem all that flawed anymore.

The third car in this trio is a bit of a joker. We love the Merc CLS 63 AMG ? Mercedes-Benz pulled a coup in the sleek (if a little banana-shaped) CLS and it really works in AMG incarnation.

Powered by a monster 6.2-litre lump, it doesn't quite match the sophistication of far more specifically powerful M5 or the brute turbo power of the RS 6, but it strikes a damn decent yet uncompromised middle ground. AMG has always sought to build on those Mercedes-Benz virtues of comfort, luxury and quality and that much shines through in this, perhaps the best balanced of all the AMGs?

Of the three, this is also perhaps the best at what we call this story ? bahn stormers ? too. There is little compromise to those CLQ virtues ? AMG squeezed that 500 horse 650 Newton-metre monster under the bonnet and it doesn?t really care that it weighs more than an M5. Or is a little less balanced. It's as quick in a straight line anyway ? once the compromise of that auto box has been overcome of course.

AMG also doesn't quite see its customers using this thing as a track day tool either, so it rather concentrates on making sure its cars are absolutely magnificent on the road, which they are.

Merc isn't shy to charge either ? CLS 63 AMG is the dearest of this bunch too, but that philosophy of keeping its owners happy on the road is probably why this thing is so popular. It has it all ? the looks, the power, the performance and the kudos. But it also falls very short in one critical super saloon criteria, and no matter how good it is on the road, to really make it in this company there is one little test that a super saloon needs to ace to make it stick in this genre?

Kyalami is a bastard of a racetrack. As a driver you need to understand the circuit?s nuances and as a race engineer you are supremely challenged to balance out the diverse needs of its various traits. So a road car has to be damn well sorted to ace Cars in Action?s unique Kyalami Hot Lap test.

And that, at the end of the day is what is going to decide this shootout.