'The Caterham 620S is a Seven that went over to the dark side and just kept going'

I have this month been pondering more often than usual the seemingly nebulous relationship between fast and fun. I have often commented on the problems inherent with most fast cars, namely that to package and harness all the power required to make them go fast requires cars that end up being both large and heavy and which are, ergo, less fun. In my more iconoclastic moments, I may even have been given to observe that fast and fun may be mutually exclusive, if not perhaps quite diametrically opposed, aims.

But then a Caterham 620S came to stay for a few days, quite clearly to expose such thinking for the utter rot some have claimed it to be. For those who don’t know, the 620S is a Seven that went over to the dark side, found it a bit too namby-pamby and just kept going. With a supercharged 2-litre engine producing 310bhp, it has a power-to-weight ratio of convincingly more than 500bhp per tonne, which is Bugatti Veyron territory.

Yet instead of occupying more road than a Sherman tank, the 620S casts the same shadow as any other Caterham, including mine. My Seven is a rather more modestly specified 1700 Super Sprint, 25 years old, and with a lump of old Ford iron under the nose producing a plucky 135bhp. It’s a bit lighter than the 620S but not much, and certainly not enough to elevate its power-to-weight ratio to even half that of its brand new stablemate.

But what I felt would be so instructive about the comparison is that so much of the cars’ specifications are the same. They have similar spaceframe chassis, with double wishbone front suspension and a De Dion tube at the back. They both direct their power rearward through a five-speed gearbox and have dimensions that in all important regards are either the same or close enough to make no difference. Really, the only enormous variation between them is that one is really, really fast and the other is not.

I set off in my car first, not because I needed to remind myself but because when comparison testing if you don’t jump straight from one car to the next, something always gets lost down the gap in the middle. Also, it is the most enormous fun and I don’t need an excuse. And as I bowled along, listening to the crackle and cackle of the little motor as it inhaled through a pair of twin-choke Webers, it was hard indeed to think how simply going faster would be more fun. These cars are about how they feel and, besides, even mine is more than quick enough to overtake almost anything almost anywhere, which of course is the principal virtue of power.

So then I headed out in the 620S and was impressed at once. I thought it would be a road-legal racing car, but it’s not. It’s set up quite soft, rides as well as my car and with thin bucket seats it’s actually more accommodating of my 6ft 3in frame. It even offers somewhere to connect your telephone and seat warmers too. I can hear Colin Chapman spinning from here.

“Maniacal in third gear and absolutely unhinged in second”

Before I drove it, I thought I’d be writing that though the 620S is certainly much quicker, it’s also less usable, and the less you use a car, the less fun you’ll have. Not so: the 620S is as usable as any other Caterham, which is actually surprisingly so. I’ve been on holiday to Europe in one.

The big difference is that if you drop a gear and floor the throttle, the 620S doesn’t just jump convincingly forward, it slams your head back into your seat. It’s pretty thrusting in fourth gear, borderline maniacal in third and absolutely unhinged in second. And it is great, great fun.

Yet while feeling it rip through the ratios is never less than utterly thrilling, you do soon get used to it. Or more used to it. Its other qualities however – the feel and precision of its steering, the poise and balance of its chassis, the strength and tirelessness of its brakes, the speed of the gearchange and closeness of its ratios – never feel any more or less special, regardless of how far you go or how often you drive. I know this because these are things it shares with my car, and they never have.

Where the 620S is incredible is in providing supercar performance in a package you can still thread down a country lane; but my old banger offers a least two-thirds of the fun, for one third of the money. Diminishing marginal returns, I guess.

Because I had the Audi e-tron this month and because I couldn’t face the ghastly Ecotricity network of electric car charging points, I downloaded the app for Ionity, Europe’s ultra-fast charging network and found just one – one! – station between the west coast of Wales and London. Situated near Chippenham, it’s half a mile off Junction 17 of the M4 in some concrete truck park wasteland where there is no shelter and only a grim and grubby small supermarket a short walk away.

But the charging experience? Oh my goodness. Tell the app where you are, which ‘pump’ you’re using, plug it in and watch electricity pour into the car. That’s it. The e-tron will charge at around 270kW, or almost 100 times faster than a three-pin plug and five times quicker than anything Ecotricity will offer you. The fact the surroundings were hardly salubrious quickly became an irrelevance. Until all UK public charging is like this, the EV revolution will continue to be artificially restricted.

A former editor of Motor Sport, Andrew splits his time between testing the latest road cars and racing (mostly) historic machinery

Follow Andrew on Twitter @Andrew_Frankel