Citroen's one-off Cactus: most comfortable supermini ever?

A French man is enthusiastically showing me two photos of a human bottom. This is a strange day at work, even by Top Gear standards. 

Fortunately, he's part of a skunkworks in Citroen that wants to do away with schporty-this and dynamic-that, and reinvent car comfort in a world that's got mired. This is the work of the Citroen Advanced Comfort squad. The bottoms depicted are in fact pressure maps, showing how good seats spread the strain on your backside, and bad seats don't. So, sit on poorly designed car seats and you go numb, and ache after a long trip. Sit on good'uns and you don't.

There's more to the, um, CAC initiative than multicoloured rump maps, however. Citroen has addressed refinement, chassis building and, sure enough, suspension components in order to make what might be the world's comfiest supermini, in the bumpy form of a C4 Cactus. And the plan is to roll its findings out on showroom models within two years.

It's worth a quick explanation of why exactly Citroen has spent three years’ worth of man hours and a torrent of euros focusing on sheer old fashioned comfort, instead of say, handling, or autonomous driving, or anywhere else the car industry funnels oceans of cash.

Citroen's research says car journeys are shorter than ever, more fragmented and a car itself has more purposes. We're all busy, we're stressed and we demand more functions. Citroen's also discovered customers tend to feel they drive more aggressively than they used to. Meanwhile, we multitask in cars now more than ever, with screens to look at and constant techno-distractions.

Bringing zen back into motoring isn't as simple as slackening off the dampers and fitting 1960s-spec wheels either. Citroen reckons comfort perceptions have changed, from just good suspension to also a sense of space, and versatility, hence the rise of MPVs in the 1990s and SUVs in the last decade.

So, although you're reading about the Advanced Comfort tech as applied to a C4 Cactus, Citroen is adamant its innovations can be transferred easily and cheaply to other cars in the range. Superminis like the C3. MPVs like the Picasso. And yes, crossovers like the upcoming Aircross. However, the engineers says it's very much an exclusive Citroen thing. DS and Peugeot can forget it.

In ascending order of complication, first off we've got comfier seats. They even look comfier – rolling hills of padding under a soft grey cloth. Your American land yacht fantasies of the 1950s are back. Except here, Citroen’s doubled the number of supporting wires that cradle the seat foam, and the stuffing itself is so dense and springy you could probably chuck a section of the Eiffel Tower observation deck, jump down after it and land without a parachute. So the seats are awesomely comfortable. They’re welcoming, supportive, and cosseting.

Next up, the chassis. It’s a lot stiffer, which means the suspension (which we’re getting to, promise) can do its job more effectively without the body flexing like a lylo on a choppy swimming pool. Problem is, adding reinforcement means piling on weight, killing economy and wearing our your tyres and brakes. So, Citroen’s gone for an adhesive process that leaves gaps for spot welds in crucial areas. It’s all done by a clever robot, and the result is a 20 per cent increase in stiffness, while saving 13kg on conventional chassis girders. 

Right, the suspension. In a nod to the classic DS’s legendary suspension (it famously saved Charles de Gaulle from assassination, dontcha know), hydraulics is at play here. However, this isn’t a complex and expensive interconnected system like a McLaren supercar’s. Citroen wanted the new suspension to be compatible with all its production models, to not add weight, and to keep costs down. Otherwise no-one’s going to spec it…

Essentially, it’s a regular damper and spring. But where the one your car likely runs around on has a large rubber stopper at one end, Citroen has a second chamber with a second, smaller spring. This effectively increases the damper’s stroke, and when it’s being compressed, hydraulic fluid is forced into the chamber to smooth out the movement. So, you get a more controlled, more long-legged ride, without everything floating around like a 1980s Cadillac with dodgy tyre pressures. It’s a promising solution, this, principally because it’s a simple one. And simple ideas tend to catch on.

Anyway, enough classroom lecturing and bottom maps. Time to actually see if the, ahem, CAC, works. First up, a 30-minute acclimitsation drive in a totally bog-standard Citroen C4 Cactus – a car certainly not sporty, and designed for comfort around town. Even its bodywork is squishy. We’re on some properly crappy (read: British-like) country lanes and A-roads about 30km out of Paris, so this is no test-track smooth-fest, and the Cactus isn’t altogether happy. You can tell it’s a light car, because there’s a fidgetiness to the car’s behaviour, some clanging resonance in the really big potholes, and murmurs from the steering wheel and the front tyres scrambles from divot to crevice. 

Normally, you’d pay it no mind, but we’re here to really pick ride comfort apart, and though the seats are still oddly pliant for a modern car, it’s not what you’d call cushty, overall.

Now, the concept car. Which, as it turns out, is an identical looking C4 Cactus. Same 17-inch wheels, same tyres, same ride height… it’s completely normal. From the outside, at last. Step into the seat’s welcoming embrace and immediately, this feels different. The seat’s cushioning is deep and luxuriantly soft. There are deep pile carpets on top of extra soundproofing to extend that feeling of luxury, so naturally, when the three-cylinder 1.2-litre engine thrums into life, it’s distant and quiet. 

But on the move, this Cactus is just uncanny. The ride is so good, it messes with your head – because this isn’t a luxury limo. It doesn’t have a football pitch-sized wheelbase or air suspension. It’s a flipping supermini, but it’s quashing bumps – genuinely vicious, craggy knolls and gnarly surfaces – like the lovechild of a WRC racer and a Rolls-Royce Phantom. It’s freakish, and all the more exciting because there’s no electronic voodoo or million-quid gadgets making it happen. Just some extra adhesive, elegant suspension, and squidgy cushions.

Oh, and it’s not just the ride. The steering is more linear, clearer too. Cars that ride cleverly tend to steer rather nicely, and this proves the point. And that bodes pretty well for the facelifted C4 Cactus, the next Picasso MPVs, and well, every other Citroen. Because this stuff is heading for them all. The seats within the year, and the dampers by 2019. Because whether we’re still driving our own cars by the end of the next decade or not, you’re still going to want a numb-free bum, right?