There’s something reassuring about the way Citroen looks these days, a range with variety and depth, and the confidence to do what it used to do as well as anyone in the industry - namely to make cars that others would think of certainly as brave, and possibly even as wacky, but which actually appealed to the market at least partly for that very wackiness.

In short, Citroen design is brave and distinctive, and when it comes off it comes off very impressively indeed. Which brings us to the French manufacturer’s star concept in Frankfurt, the C5 Airscape, a drop-dead gorgeous drophead cabriolet that looks like a very expensive offering indeed and which is quite clearly a strong taster of a future production car.

The word beautiful is not inappropriate here, because the clean lines and near perfect proportions are exactly that. The Citroen identity is strong, too, especially in the nose with its double chevron theme – which insiders say is virtually identical to what will eventually appear in production form. And there’s no reason, either, to expect that much else will change in any dramatic fashion, so this is a car you’re essentially likely to see a lot more of. The folding roof is made entirely of carbon-fibre and includes a glazed front section that lets more light into the car but is the one element of the styling that currently looks a little bit uncomfortable. That aside, though, and you’d be very hard pushed to find fault with the overall shape or detail.

It is technically interesting too, of course, in the same spirit of Citroen individuality. The interior is as handsome as the exterior, and the control layout is imaginative but promises to be very functional. The car is powered in part by a V6 HDi diesel engine with particulate filter and the ability to run on biodiesel, which drops it neatly into the Frankfurt 2007 theme. It also has a ‘Snow Motion’ traction control system that they say offers performance close to that of four-wheel drive – and (did you guess?) UrbanHybrid technology, including reversible alternator-starter functionality for low consumption and emissions. We loved it.

Hard to say the same for Citroen’s other concept, though, the C.Cactus, which they describe as ‘a new ecological and attractive take on the essential car’. That does not, however, excuse its almost cartoon ugliness, or the wilful silliness of an interior theme based around either stylised green dragonflys or marijuana leaves, carved into several surfaces.

They’ll say that what’s really important is its clever construction with an unusually small number of components, its high levels of recyclability, mats made from re-cycled leather from tannery off-cuts, a refillable scented air-freshener, loads of room and a diesel hybrid powertrain that gives a combined CO2 figure of only 78g/km. But it isn’t pretty.

Still, when it comes to concepts, getting one out of two right isn’t really bad.