This is one of those highly tricky moments. It’s all relative I grant you, since driving sports cars back-to-back is better than emptying bed and or working off the cost of your illegal immigration as a sex slave, but it’s still frustrating at times. This summer, the new M3 was launched and we took it to the Isle of Man to dick about with lots of other similarly impressive cars – again, not a career low point, I know – and I seriously rated it. It was far from the most expensive car there, but still one of the most capable. It was, to all intents and purposes on that rain-soaked rock, the best car on sale, pound for pounding pound.

Then we wheeled out the Cayman S and were in the same place we started, two years ago, when the Cayman S went head-to-head with the RS4. Exactly the same in fact. A day spent nailing the pair around the Downs, coming up with the same conclusion at every corner. The Cayman is the one that’ll take you around it, flat and full of confidence, while the M3, even more so than the RS4, is the one that will roll a bit and probably have warranted a pre-emptive dab of brakes beforehand anyway.

In a straight squirt the Cayman pulls away too, but in those corners, short of a level of heroics this road tester readily admits to lacking, it leaves the M3 at an apparent standstill.

The hook here is that with all their bells and whistles both cars are around the Rs 42-lakh mark - eye-watering stuff for the most of us, but still manageable for the fortunate few. Much less than a 911 or V8 Vantage too, and bolstered by shit-hot performance and plenty of kerb kudos. However - and this is a point that needs stressing - the fact that the M3 has four seats does not make it exempt from a Porsche-shaped shafting. Everyone needs to dismiss the notion that this thing is practical. Those rear seats won’t do for much more than tiddlers, and access is hopeless for any proper child-seat shenanigans.

No, what the vast majority of M3 buyers are after is a monstrous turn of speed. And that you get. But is it going to make a difference to the hollow lives of the scores of avaricious estate agents who are already salivating at the prospect of ownership? In the same way that I can guarantee a Cayman would? No chance. The thing is, the M3 is a great car, in so much as it is very fast, very comfortable and very approachable. And it still looks special and carries enough clout to impress those in the know. But accept that it's not really any more usable than the Cayman for the sort of person that buys a pricey performance car, and the Beemer is rubbish by comparison. After all, when you buy said performance car you really want to know ~bout it: flat six hollering behind your head in a snug, focussed sports car cockpit. Superbly direct steering feel, near-perfect balance, and an appearance that significantly singles your car out from the backdrop of three-box saloons around it.

BMW has made a rod for its own back. Engineering a new and complicated V8 package has, perhaps alongside conscious market realignment, led to a Rs 30 lakh car becoming a Rs 40 lakh car from the last generation to this one - a serious sting in the tail for devotees of what was formerly a unique prospect. Spend 40 big ones on an RS4 or Rs 10 lakh less on the last M3? That would have been a no brainer for almost anyone. No longer...

But there's little point contemplating the 'what ifs' now. BMW has moved itself up a weight division, taking the fight to Audi, Mercedes and, oops, even Porsche. And it can’t come as a total surprise that it's currently losing every bout. Mercedes has been here before with a previous incarnation of the V8 saloon. Audi, meanwhile, has the advantage of Quattro four-wheel drive and the head start of establishing itself earlier when the market was bereft of rivals. And as for Porsche, it set about building a fixed-head two seater with the tight-as-a-button Boxster as its template. Without taking anything away from the Cayman, it doesn’t get much easier than that. We all haulked at how much Porsche dared ask for a stiffened Boxster, but it hasn’t slowed sales any. But BMW had a workaday saloon to fix up like Audi and Mercedes, albeit a finely honed, rear-wheel-drive job with a better chassis than the others. It also had none of the V8 know-how that Mercedes-Benz and AMG had advanced in the C63, and fewer inherent handling advantages than the super-sticky RS4.

And yet, for all that, BMW's done a superb job and this remains a deeply impressive evolution of its own legend. But in the final analysis, I can't help but feel that people are going to struggle to write cheques for M3s that would also get them RS4s and AMG Mercs, let alone Porsches - although as Bill pointed out, such a verdict may be revised with the arrival of the four-door M3 next March.

As it is, forced to decide between Cayman and M3, no force would be required. In every imaginable respect the Porsche is a superior sports car. And as for those absent back seats, bugger it. Just pack a little lighter and don't have kids. The payoff is good enough to justify a vasectomy.