Fast forward nearly 40 years and the M3 GTS will soon be delivered to customers for a whopping £117,630 – more than twice the cost of a regular E92 M3. Perhaps BMW GB recalled the 1972 CSL episode when it decided on UK sales volumes – it looks like there will be fewer than 15 GTSs registered in the UK.

In 1972, the importer for BMW ordered several hundred CSLs, but famously added a few creature comforts in an attempt to broaden its appeal. The price was £6399; at the time a Jaguar E-type V12 was £3387. And this was the vanilla CSL, not the crime-against-the-Hofmeister-kink you see on these pages: the full Batmobile. No, by the time Bats were delivered in 1973, complete with larger 3153cc motor and decidedly un-road-legal spoiler sitting inside the boot, the pound had weakened and the car was knocking on for £8000. Unsurprisingly, many remained unsold and weren’t registered until later in the decade.

But there is another, less salubrious link between these two – uncharitable souls might suggest that the CSL and the GTS rank amongst the most eye-poppingly overpriced performance cars ever sold in the UK.

You wouldn’t be wrong to think that the most obvious connection here is motorsport. In 1972, BMW needed a machine to make it competitive with Ford in the European Touring Car Championship, so it created the 3.0 CSL (‘L’ standing for leichtbau, or lightweight). With it began a lineage of spectacular road-legal machines, designed primarily to operate on a racing track, a lineage that can be traced directly to the new M3 GTS…

To fully understand the visual impact of a real Batmobile on the public highway in 2011, you need to drive through rural Wales in one, preferably in convoy with a bright orange M3 GTS. It’s a piercing hue, that tangerine shade. Factor in the lower suspension and the bootlid protrusion and, merged into UK traffic, this most extreme E92 has the look of an Amazonian parrot in a flock of grubby starlings. Even so, no one even gives the new car a second look as the CSL burbles past, its grotesque aerofoil section flexing over bumps. Inside, snuggled down into that bucket seat, I’m wondering if I mightn’t prefer a CSL to a 2.7 RS.

The difficulty with old metal is approaching the way it drives with any objectivity. The CSL is a car I wanted to understand in a 2011 context, if only because that other famous homologation special from the era, the aforementioned 911 Carrera 2.7 RS, sustains its appeal and value because it still feels surprisingly competent at speed. But when you approach the CSL, you giggle at the body alterations, clink the little metal door-handle open and fill your lungs with the unmistakeable pong of vinyl-impregnated air. If your objective intentions aren’t already shot to bits, then they soon will be: that shoulder-cut bucket provides the perfect, suggestively laid-back ’70s posture, the leather-trimmed wheel is thin and delicate, and there’s no slack at the straight ahead. The motor takes a few seconds to fire, but does so cleanly, settles to that trademark Bosch-mechanical-injection-idle and, if you weren’t already snared, you now will be.

The throttle weight is just perfect; prod lightly and the VDO rev-counter leaps. The straight-six makes a gruff rumble, but at low revs is partially obscured by the noise of the cooling fan. The steering is comically heavy at low speed but all it takes is 15mph showing on the speedo for the wheel to free up and provide the driver with an experience unavailable in any modern car. The rack is slow, but that doesn’t matter in the context of the CSL: it is quite perfectly matched to every other control. And to think that non-Batmobile CSLs are still well under £50K – what a bargain.

When conversation turns to early-’70s race specials, everyone thinks of the 2.7 RS and its ducktail bootlid, but the CSL was by far the more radical machine, even before it sprouted rubber sideburns, because the car on which it was based, the 3.0 CSi, offered far less performance than a 911 2.4S. The CSL body was built using thinner-gauge steel, the bonnet and boot panels were aluminium, the side windows were Perspex and there was no underseal. The metal rear bumper was ditched for a piece of plastic, the front bumper binned altogether. In all, over 200kg was shaved from the 1374kg kerb weight, but that wasn’t enough to beat the all-conquering Ford Capris run by Jochen Neerpasch and Martin Braungart in 1972, so BMW did the sensible thing and bought the human expertise too.

Neerpasch and Braungart joined BMW, creating the business that is now BMW M GmbH. Their first move was to push the boundaries of the homologation rules and develop the aero package you see here. It worked: BMW won the European Touring Car Championship in 1973, and the red, purple and blue flash would become synonymous with fast BMWs from then on.

The CSL’s main problem in the current marketplace is one of mechanical ordinariness: that straight-six may have been taken out a few cc, but there wasn’t any claimed increase in performance – it was timed at 7.3sec to 60mph and wouldn’t quite reach 140mph. That last figure was hampered by all those lumps ‘n’ wings, and the standing-start times weren’t helped by the boot spoiler – which weighed so much the bootlid had to revert to steel just to be able to support it.

I’m surprised how pokey it feels today. The immediacy of the throttle adds to the impression of speed, but it has heaps of torque (215lb ft) and four gear ratios that might have been designed for cross-county adventures in 2011. Within a few miles, I’m smitten. Like anything old and unassisted, the car is only as good as your inputs, and you quickly focus your attentions on the areas where you can make the most difference – matching revs on each downshift and, moving up through the gearbox, hanging just a few extra mm of throttle to make the clutch re-engage smoothly. The shift exposes all that is wrong about modern, short-throw manual changes: there’s no obstruction, just a lever that requires shoulder movement and whose lengthy action reminds us that the longer the shift, the longer you have to enjoy the sensation.

The car wants to rev too: it pulls strongly from 2500rpm, builds as generous helpings of induction noise blend into the cabin through 3000rpm, then assumes a more aggressive tone all the way to 6000rpm – and it’s worth using all of it because the reward is a car that to me feels faster than the claimed figures. It isn’t 2.7 RS quick, but so what? Of far greater significance is how different it feels to a Porsche. There’s less mechanical grip – the 195-section rubber squirms about and you apply small amounts of corrective lock at quite high speeds – and all the while you’re ensconced in the wee bucket, afforded unrivalled visibility past the skinny A-, B- and C-pillars and using those wing-mounted strips to guide you.

Cars are getting louder. We all think wistfully of straight-sixes snarling around European race venues, but when the GTS fires on the moor, walkers assume the arrival of another low-passing Tornado. BMW has remained tight-lipped about the reasons for making so few GTSs (150 in total), but you’d have to assume that certain aspects of the package were only suitable for low-volume type approval, and the most obvious is the noise. From header to tailpipe, the exhaust is undiluted Akrapovic loveliness, and there is not the vaguest hint that it complies with any drive-by regulations. I am entirely cynical about the price of the GTS, but with all throttles open, from 3000rpm to 8000rpm, it might just be worth the money.

The exclusivity can’t be ignored either. Just as I find it difficult to move beyond the trinket-like appeal of the CSL’s chrome details, so the knowledge that you will probably never see a GTS on the road in the UK does somehow add to its cachet. It’s an emotional response that quickly subsides once you’re driving, though – in fact it dissolves and hardens your resolve in the opposite direction. It’s a crime that more of these cars weren’t built and the unit cost didn’t tumble as a result. The 997 GT3’s legacy would not have been so glowing with such competition around.

Does it feel aloof and computerised after the CSL? I think that’s too banal an explanation for the differences between the two – perhaps the key word is ‘consistent’. The GTS offers its driver a level of consistency through its controls that was unimaginable 40 years ago: regardless of load, angle or speed, the steering is heavy but precise, the throttle heavily sprung but instantaneous in its response. The sharp, near-perfect shifts from the DCT transmission only add to the feeling of imperious consistency, and as a driver it’s impossible not to be impressed.

In the CSL you moderate your inputs according to the conditions, largely because you can’t be entirely sure what mood the car will be in – under load into a turn it might be a little reluctant to shift from third to second; the inside-front brake might grab slightly and the throttle could require some added shove. So you improvise – you glean what you can from the information available through your hands, bottom and feet and you adjust your inputs accordingly, because the controls never remain consistent. That’s the joy of classics.

The GTS really is the anti-GT-R, though. As honestly rear-driven as any car on the planet and easily as strong as its 444bhp would suggest, I challenge anyone not to drive it with some level of oversteer. Owners will need to be followed around by a large Pirelli truck.

It is a very different machine to the base M3, or even the Competition Pack version. The geometry changes have wrought much more steering weight and feel, there’s less understeer and less ride comfort. The dampers and ride-height are adjustable too, so nothing is definitive. As presented, it lacks the suppleness of a GT3 RS, but is similar to the Porsche in that its overall road manners are so palatable that each glance in the rear-view mirror comes as a slight shock: it reminds you of the deleted rear seats and bolt-in roll-cage.

Small volume means high price, and anyone who competes in motorsport will understand how easily a £55K M3 can become a £120K machine without looking too different. The extendable front splitter is a nice touch; the extensive chassis changes are expensive, and Akrapovic exhausts cost a fortune. But, as an object, the GTS remains a disappointment to me: the orange engine cover is crass, the rear spoiler is the aerofoil equivalent of a teenage trouser-bulge and, apart from the cage, buckets and build plaque, the interior is too similar to a base M3 given the vast price difference. It was comprehensively beaten by the GT3 RS in evo 150, and, unlike the CSL, it doesn’t exist to facilitate BMW’s entry into a specific race series – although it is pretty much a road-going version of the GT4 race car.

For the few owners, none of this will matter. They will have in their possession a car that looks and sounds unlike a normal M3, plus all the future benefits of low volumes. Everyone knows that scarcity is the secret to long-term financial appreciation. The GTS doesn’t have the narrative to support its existence, though – whereas the CSL will always be the car that laid the foundations for BMW M, the machine that beat Ford and which begot perhaps the most bizarre set of spoilers ever plastered onto a production car.