BMW’s M3 has long been a signifier of success. At a certain point in life you get your 3-Series, then, presumably after selling lots of... stuff (paper, houses, crisps, whatever) to the public, you get the one with a big engine.

After that you either have a family or buy a Porsche 911. Still, an M3 on the drive is a sign that things have gone well and that you have good taste in cars.

The turn of the century saw BMW refresh its 3-Series. Out with the E36, in with the E46. Naturally, the new, higher E number meant there was a new M3.

The E46 M3 was a blinder by all accounts, with a 3.2-litre straight six that won award after award and propelled many a happy fool sideways around bends. It was a Good Car.

BMW, in case you hadn’t noticed, loves to tinker, so after deciding the regular M3 was sorted, it got to actual work and created the M3 CSL (Coupé Sport Leightbau).

It’s the E46 M3 you actually want but almost certainly can’t afford because too many other people have the same idea.

The reason for the demand? BMW went to town making it the best it can be. On the family-car-to-touring-car scale, the standard M3 leans towards the sporty end, sure, but the CSL? It’s hunting the touring car and then some.

BMW took a regular M3 and gave the engine 355bhp and 273lb ft (a moderate bump over the standard car) thanks to a ram air intake in the bumper to feed it cool air, fresh camshafts, a new exhaust and lots of engineering know-how that’ll make a normal human’s brain go all swimmy.

On top of that, BMW’s M Division stripped 110kg out of the base car’s near 1,500kg weight thanks to things such as thinner glass, carbon fibre in strategic places, fibreglass seats, less sound deadening and a bit of a talking to about diets at point of sale.

BMW fitted a quicker steering rack and, at each corner, stiffer suspension and trick dampers to help it go around corners quicker. A chin spoiler and more extreme boot lid lip aid downforce.

Inside is a feast of carbon fibre and (in UK cars) a commemorative plaque to let you know you’re in something special.

There are no huge intrusive screens, no digital dials and good luck finding a USB slot. It’s unfussy, uncluttered.

While you’d expect a modern performance car to come with an automatic (usually a “faster than a human could ever manage” dual clutch), in 2004 you didn’t.

At the time, fitting an SMG (automated manual) six-speed ’box to something with so much going for it was regarded as something of a foolish move.

The ultimate E46 M3 was off to a good start: looking suitably different to the base car so that fans would go weak at the knees on sight, while still appearing enough like “a car” that you wouldn’t get any unwanted attention.

Turning the key, a novel thing these days, gives you a burst of glorious noise. The pipes on this thing are something else.

A hollow, high bark fires out of the rear, echoing through the cabin, vibrating along its length with a savage delicacy. It’s an angry sound.

Though it doesn’t show its full range until about 3,000rpm. From there you’re encouraged to shoot as much noise as possible from the back as often as you can.

With a 0-62mph time of 4.9 seconds and a 155mph top speed (unless you had a race licence, then you’d get 174mph), it’s hardly a slowpoke.

Though, yes, you can get a Golf with silly power and jazzier numbers, from the off this thing feels special in a way a hatch never will. Putting your foot down, there’s no turbo torque slinging you up the road.

It’s wonderfully linear and feels light on its feet. The steering, quick rack and all, feels a little light until you prod the “Sport” button, which throws a bit more heft to it and peps the throttle up a touch.

Though its power may seem modest by today’s standards, the CSL enjoys flinging its horses out of the rear wheels with haste.

Tipping the car in to a corner and giving it a smidge of gas feels fantastic – the rear hunkers down and you’re fired forwards in a cloud of noise and, probably, giggles.

Though it’s decently grippy, it doesn’t take much provocation to annoy the traction control. BMW added an “M Track” mode (a relative of today’s M Dynamic Mode) that lets the car move around a little more before the stability control steps in – ideal for getting to know your CSL a little better on a circuit… or to show off down quiet B-roads.

What will likely grab you is how small it is – the old 3er is a dinky car, yet feels huge inside.

BMW’s decision to fit heftier brakes to the CSL was a wise one. They feel chunky and do their thing rather suddenly – a good thing if you find yourself enjoying the car a little too keenly.

With a drive as wonderful as it is, it’s no surprise that it’s so sought after. But there are a few downsides. It’s not the comfiest thing in the world, which is to be expected, but that may grate after a while.

Its fibreglass buckets may be lighter than a quaver, but they also knacker your back after a short while. Finally… the gearbox.

The six-speed SMG wasn’t the best back in period and it’s not brilliant nearly two decades later. It’s slow, clunky and simply tough to love.

If you keep your foot pinned as it shifts you feel the car drag itself from ratio to ratio.

Of course, if you treat it as a manual, guessing when it’s going to change and lifting when it’s doing its thing, you’ll have a better time, but it’s just not aged well.

Having a look at the CSL now is fortuitous as BMW has just launched the G80 and G82 M3 and M4 Competitions, each powered by a turbocharged 503bhp 3.0-litre engine, with power delivered to the rear wheels by an eight-speed auto.

Where the CSL is scrappy, shouty and in your face all the time, BMW’s latest and greatest is more grown up and composed.

Yes, it’ll make a decent noise and likes to move around, but the new car isn’t one your mother will judge you for owning. The E46 CSL, however… she may have words about.

The new car is a mass of ones and zeroes that all do interesting things. There’s an M Drift mode in the modern car that ranks your slides (where safe and legal, of course), while the old car… it’ll let you know whether you screwed up your skid if you smack into a tree.

The new car can make you feel like some sort of deity but is very much packed to the rafters with things to keep you safe. The old one? It does performance the old-fashioned way.

BMW’s E46 M3 CSL is a truly special bit of kit – and one that doesn’t look quite so challenging as BMW’s latest models…