As I write I have just stepped out of a room in which I have been fantasy-specifying an Alfa Romeo 33 Stradale. It's something all of this model's 33 customers have done: the level of personalisation available is at the 'if you want it and it's feasible, they'll do it' level. But they won't tell me how much one costs at the end of it.

The 33's 'few-off' production run was sold out not before the car was announced but before it had even been designed or approved by Alfa Romeo (and Stellantis) bosses.

It's a - let's call it - £2 million supercar from a car maker that also sells a £30,000 crossover, and yet somehow it seems like a totally reasonable proposition from a company with this badge. It's also very good.

To recap, then. Potential customers - collectors, Alfa fans - were first shown sketches of the 33 Stradale in 2022 and said they would love one, thanks. Their input - and I don't think this is just puff - was taken on board during the next phase of the design process. Alfa formed a committee - the Bottega - to oversee limited-series production once it was approved. Camilla Rostagno, Bottega's head, said: "We were like a start-up: agile and fast."

By the time we saw the 33 Stradale in 2023, the first customer delivery had been earmarked for 17 December 2024. That's a remarkably short time, to the slight consternation of chief engineer Jean-Philippe Delaire, formerly a senior engineer in Citroën's WRC team and later the man behind the entirely decent Peugeot 508 PSE.

This is where it was "useful being part of a big company [in Stellantis]," says Rostagno, talking to me at Alfa's Balocco test track, located between Milan and Turin. It meant the team could leverage "best-in-class" hardware, says Rostagno, "so we had something to start with and worked to make it a true Alfa Romeo".

If the same architecture, platform or modules can underpin cars from ostensibly very different 'normal' brands, why not use one brand's supercar as the basis for another brand's? Especially given that the car in question, the Maserati MC20, was meant to be an Alfa in the first place, according to some sources (although not according to Maserati, inevitably).

The result is this two-seat, mid-engined Alfa Romeo 33 Stradale coupé of unknown but expensive price and such exclusivity that more than 50 people remain on a waiting list even today, just in case. Perhaps they will get the next car.

Beneath the 33 Stradale's covetable curves - you can spec whether you want the rear wing cut away, as here, or left intact - lies the carbonfibre tub of Maserati's MC20 Cielo convertible (selected because it has more strength in its lower section than the MC20 coupe's monocoque), to which an Alfa-designed aluminium X-frame is mounted above to support the roof. The X-frame also gives a locating point for the upper of each door's pair of hinges. Doing it this way increases door rigidity and removes any tendency to lift at speed.

To the tub's rear is a modified MC20 aluminium subframe - again cross-strengthened - that houses a tweaked 3.0-litre MC20 engine. The twin-turbocharged V6 makes 621bhp at 7500rpm and is mated to an eight-speed dual-clutch automatic transmission driving the back wheels via an electronically controlled limited-slip differential.

The by-wire brakes are via standard carbon-ceramic discs, 390mm in diameter at the front, 360mm behind, with 20in aluminium alloy wheels offered in three designs, all shod with Bridgestone Potenza tyres: 245/35 ZR20s front, 305/30 ZR20s back. All-round double-wishbone suspension is sourced from the Alfa Giulia GTA, with 33 Stradale-specific settings.

There are two drive modes, Strada and Pista, with 'ESC off' available in the latter; damper modes are soft or medium in Strada, hard or a different medium in Pista. Production, taking place at supplier Carrozzeria Touring Superleggera, ramped up gradually after that first delivery and is very labour intensive. The last 33 won't be made until late next year.

So why are we driving it now? Because they asked us to, is the short answer. But also the Bottega division was last November officially incorporated to make low-volume and one-off cars for both Alfa and Maserati (the MCXtrema is the Trident's first), plus there's a chance we will see the second few-off Alfa later this year and this is an opportunity to remind us about it.

Either way, I'm very pleased with the light blue metallic 33 that I specified on gold heritage wheels, with a biscuit and brown Alcantara/leather interior and about which I would change my mind by tomorrow morning. How on Earth do buyers nail down their chosen specifications for these cars? Not all do: one person agonised for eight hours over theirs; others make changes shortly before production starts. One called back the day after his highly satisfactory spec session to say his wife didn't like it. Even billionaires answer to someone.

So what's it like, this delicious north Italian slice of unobtanium? Great to sit in, for a start. The generous door glass makes it wonderfully airy, even though it's compact. The low scuttle reveals those shapely wings. I've been told by Delaire to make allowances for the fact that this is car zero of 33, so it's the 34th 33, the only prototype, and a few things have been amended for what counts as production. "We didn't have 'few-off' levels of quality when we started," admits Rostagno. "We made a new benchmark specifically built around this type of car."

Only a fabric join on the dash top looks in any sense awkward in here, and it has since been resolved, I'm told. The rest of the perceived material quality is bob-on.

They have learnt a few lessons on the way: initially the door release button wasn't secured well enough for people who tried to pull the door closed by the small leather strap attached to it; and there's a touchscreen for the temperature and audio, whose mechanism to slide it up into the dash has been beefed up. I like how it stows when you don't need it.

The vents are hidden behind a diagonal on the dash, so you can't adjust where they're blowing, but this is the kind of car where that bothers me not too much. Better - brilliant, even - are the centre console and overhead buttons and toggle switches, finished in aluminium. They're positive to the touch and easily grasped, while the action of the rotary start-stop button is as nice as any switch in any car.

The steering wheel, too, is an aluminium three-spoker devoid of any buttons on its front. Wondrous. And do I detect the 33 team taking a certain pleasure in the fact that the wider industry is now following the trend of this tiny-volume sports car?

And a sports car it is. Perhaps a supercar: it can do 207mph (333kph), after all, and 0-62mph in 3.0sec. But does supercar horsepower have to start with a seven or more these days? The 33 has 'only' six cylinders, there's no electrical assistance, it has luggage space front (thin) and rear (hot), torque is spread broadly and weight is around 1600kg. Aerodynamic addenda serve only to make the 33 lift/downforce-neutral. It's not a hardcore, super-fast or aero-heavy car, then, as most supercars are.

There's more. Buyers have been coming to Alfa - they know them all well, of course - to say how surprised they are, pleasantly, to find the 33 is easy, unintimidating and refined to drive.

I find the same. My drive is on one of Balocco's handling tracks: it's smooth, hot and dusty and the kind of place where the clumsy-in-the-UK Alfa 4C probably felt really good. So some caveats, then. But generally the 33 Stradale is terrific. I'd describe it as MC20-adjacent, which I mean as a compliment: Maserati's (junior?) supercar has an old-school, perhaps old-fashioned feel to it, with an honesty and straightforwardness that isn't evident in every new sports car or supercar. And the 33 moves that theme gently onwards.

The engine breathes deep and gets going early. Is there some lag at low revs? Certainly, but pulling a lower gear ratio, or making sure you're in it in the first place, is simple enough. The engine is sonorous for a blown six that meets Euro 6 emissions levels and thus wears petrol particulate filters. Delaire's brief was to make the 33 sound as good as the V8-engined 8C - rather unfairly, because that had eight cylinders (obvs), no turbos, no PPFs and a generous exhaust length in which to develop the sound. This V6's gases are muted and ushered quickly out. That the 33 sounds as good as it does is an achievement.

It rides, too, I think. It breathes with the surface, albeit by no means silently. It's a carbonfibre tub, after all. It's a little noisier and lumpier in Pista modes, but I think the extra control is worth it on a circuit.

It steers cleanly, communicatively and relatively lightly by the standards of, say, a Porsche. There are just over two turns between locks and the turning circle is wide. It turns willingly, at its limit nudging into steady-state understeer, as I suppose it should.

Brake pedal feel is very firm: "If you don't press the pedal, the car won't stop," deadpans Delaire. Settle the front end by modulating turn-in speed and the e-diff will help hook up the 33 Stradale nicely on the way out of corners.

But there is a relaxed trustworthiness to it. I can see why owners, many of them self-confessed collectors and enthusiasts rather than drivers, have come back satisfied. I think I would too. Maybe metallic olive green next time.

Alfa Romeo 33 Stradale

Verdict: Beautiful outside and in. Drives in an MC20-adjacent style with ability and confidence. An interesting project, lovingly executed