Extraordinary car, the Citroën Berlingo Multispace (your very best French pronunciation for “Multispass”, please), though you could argue that it isn't really a car. Technically, it's a plumber's van with the plumber taken out and windows put in. Friends won't be entirely sure whether you've come round to visit or fix the boiler. There has probably never been a vehicle targeted more specifically at the person with both a young family and a sandwich delivery business.

But why not pack up your family in a van? Vans have much to offer a family. Huge amounts of space, for one thing. The Berlingo has sliding back doors and, with both of them open, you could walk right through the car and out the other side, almost without breaking stride.

Vans are conveniently cheap, too. Yes, they aren't famous for comfort. But Citroën has thought of that, fitting the Multispace with seats and carpets and with a suspension that doesn't automatically throw you at the ceiling and toss your folded newspaper off the dash every time you hit a bump. They've modified its van-ness, in other words, though it's still plausibly somewhere you might go to release your pent-up inner postman.

There are prettier places to put a family, it's true. As ever in the making of an MPV, form has been sent into the ring to fight the eternal boxing match with function. But on this occasion, function has put form on the floor with a massive uppercut within the opening seconds of the bout. Frankly, form never stood a chance. Take those back windows, for example. Are they cutely triangulated design statements, crafted to accentuate the fluidity of a tapering bodyline? No, they're huge sheets of glass for looking through. They flood the back of the car with light and offer your rear passengers a panoramic view of all the cars overtaking you. That's the point of them.

Or take the back door. Is it a sculptured, concave conversation piece, modelled on the Sydney Opera House? No, it's a big back door, as flat as an allotment and about as large, and intended to make access to the boot so easy that passing pedestrians could almost end up in it by mistake.

Yet the whole Multispace package takes on a strange, inverted charisma, the more so for being liberally sprinkled with tokens of the slightly barking genius that has characterised Citroën since it first put a canvas lid on a sardine can and called it a 2CV.

The Multispace imagines family life as, essentially, one enduring storage problem. It may be right. Either way, if you can't find a drinks holder and a cubby hole for your orange Tic-Tacs, then you're not looking hard enough. The entire centre console lifts out, making, Citroën suggests, a handy, if unromantically plastic, picnic hamper. There are drawers under the seats, holes under the floor.

And above all, there's the Modutop. Why (Citroën has clearly asked itself) should all the fun of stowing things in overhead lockers be confined to passengers on aeroplanes? So a row of plastic bins runs the length of the car, attached to the underside of the roof.

Personally, I'm not sure I could ever learn to refer to it, unselfconsciously, as “the Modutop”. “Where's my other trainer?” “Have you looked in the Modutop?” Somehow this is not a conversation I could imagine myself casually having. “Modutop” may be destined to be one of those words, like “moist”, “wipes” and “Cristiano Ronaldo”, that people are always going to feel slightly squeamish about saying.

Even so, it's a striking feature, whatever you want to call it, and no less loveably eccentric for including, near its back end, a built-in scented air-freshener, enabling the gentle aroma of rosewood to waft across your children. Nice touch. Mad, yes. But nice.

However, surfers (among others) may wish to ditch the Modutop altogether and investigate Citroën's unique “internal roof rails” system, another stroke of individual brilliance which, essentially, invites the roof rack into the car. This way you get to stow your surf-board/ boat parts/ oil paintings where thieves can't easily walk off with them and where the wind won't play a continuous and eventually agonising cello solo on them while you're streaming up the motorway.

It goes without saying that Citroën points the Berlingo at people with “active lifestyles”. Some people might argue that a properly “active lifestyle” would centre on walking, rather than driving. Are you kidding, though? We're going by van.

Top speed: 105mph

Acceleration: 0-62 in 12.5 seconds

Average consumption: 50.4mpg

CO2 emissions: 147g/km

One careful owner: Adam Crozier

On the stereo: Radio 5 Live

In the glovebox: Twix

Bound for: Rouen

Price: £10,995