Right from the start of McLaren’s road-car enterprise, one issue was clear. This has been such a focussed company that its cars are probably too similar. They all use versions of the same tub, they all use mid-mounted turbo V8s. McLaren has no 2+2s then, no front-engined cars, no V12s or V6s.

Now you might argue Ferrari doesn’t do its great name much good by making the California, and that it makes no money from the FF (now GTC4 Lusso). But that idea – “different Ferrari for different Ferraristi” as Luca di Montezemolo put it – does give Ferrari a breadth that McLaren doesn’t have.

I’ve just been driving two McLarens side by side, the 650S and the 570GT.

Because the P1 and 675LT lines must now sadly be shuffled off to the ‘legacy models’ list, the 650S Coupe is currently McLaren’s top-end supercar, its fastest and most hardcore machine.

The 570GT is the softest. The one with a hatchback, more supple suspension, and generally less drama.

And you know what? I preferred the 570GT. The cheaper, slower one. And not for the reasons you might guess. Not because of some consideration of ‘value for money’… what’s an extra £50k at this level? Not because the 570GT was obviously a more useable and agreeable everyday car than the 650S.

But because the 570S was simply more fun overall. And in the areas where the 650S was better, it was better by a perilously slim margin.

Yup, the 650S is faster. But not much faster. Here are the raw numbers. For 0-100kph it’s 3.0secs vs 3.4secs. And for 0-200kph it’s 8.4secs v 9.8secs. Basically, both cars are awesomely quick. And independent tests have them closer than McLaren’s own figures which I’ve quoted.

In either car, out-of-corner acceleration is limited by traction, and overtaking ability by road conditions and a general need not to behave ridiculously.

It’s true the 650S sounds a bit more awesome, but since the GT is marginally slower to accelerate you get the pleasure of hearing its noise for longer. Plus, because the GT isolates you better from tyre noise, most of the time you’re hearing a purer engine sound rather than a messy roar.

The 650S has more grip. Its lap times are less, but again the margin is tiny. Both cars have carbon-ceramic brakes, so they stop insanely well, though the 650S’s pop-up rear spoiler will doubtless drag it back from road-irrelevant speeds with more aplomb. Still, gotta love the thing appearing in your mirror as you approach a roundabout.

I swear the 570GT is just as tactile on the road. You can feel it with a little more clarity. And wriggle around the grip limits with slightly more abandon. It’s adorable.

Meanwhile, for the 98 percent of the time when the usual constraints of road driving mean you can’t go like that, the 570GT’s margin is clear.

Although it does without the 650S’s clever interconnected suspension, it still has a surprisingly supple ride. And because there’s much, much less tyre noise, you’re lulled into the impression it’s a more comfortable car.

Step in – which is easier in the 570 because it has a bigger door opening – and it’s easy to see which is the newer one. Their general furniture is similar but everything in the 570 has more flowing and stylish lines. Evolution has been steady but pervasive. You even find a new set of switches for the active handling and powertrain systems.

The 570 has easier logic to its infotainment, although that’s just as well because it now has to shoulder the weight of controlling the climate, where the 650 has separate buttons and knobs for that. And the 650S lets you configure a more racy set of instruments on its TFT screen. So the older interior isn’t entirely without advantages.

Behind your head, the GT has a genuinely useful luggage bay, which means if you’ve got several cars but need to take some gear wth you, you’re less likely to have to leave the McLaren at home. Better to be in a slightly-less-fast McLaren than no McLaren at all, eh?

So the 570GT is more refined, more modern to look at, and crucially, somehow more modern to drive. To my taste it’s the better sorted and the more enjoyable. But (if you drove at night to blind you to the differences in their cockpits) really the 570GT and 650S just feel like two slightly different versions – both very wonderful, let’s not forget – of the same thing.

They’re far more similar than a California to a 488. Or even a 911 Turbo to a GT3, let alone a Panamera Turbo S to any 911. Or a Huracan to an Aventador. Or a DB11 to a V12 Vantage. You see where I’m going?

I think it’s a weakness of McLaren’s range – and I’ve thought so ever since, even before the MP4-12C went on sale – that company bosses said they’d use the same basic format for all their cars.

Still, things happen fast at McLaren. The firm just announced a limited edition called BP23 which has a tub different enough that it can seat three, with a central driving position. (Though McLaren still says it’s not a V12 or a manual or a light car by McLaren standards, so it’s not a ‘new F1’.)

The next ‘Super Series’ car – the 650S replacement – is out next year. It’s codenamed P14. And we gather it has some significant differences and developments.

I wonder if that will be enough to put clear water between it and the brilliant, and over-achieving, 570 lineup. “The same idea but faster” is not, IMHO, enough.

- Paul Horrell