The Citroën Revolte concept was one of the highlights of the show and another concept that polarizes opinion. For some, the Revolte appears as a 21st century take on the legendary 2CV that's been slammed and customized as a hot rod. Of course, Citroën concepts are never that simple and talking to design manager Carlo Bonzanigo, it was clear there's a far deeper background to this car, which merits explanation. "We know the 2CV still has big following in Germany but the IAA is a difficult show for non-German brands" he explains. "We therefore like to provoke a bit, with something that's small, witty, tense and feminine".

The Revolte mixes Parisian city culture with specific 2CV references such as the rounded rear door line, a fabric roof, tailgate strakes and square tail lamps. The front end is the most controversial area, with its mix of baroque chrome grille and Hi-Tech eyebrows over the lamps that subtly suggest a rounded lamp graphic. But there's a wealth of new ideas here that merit further inspection: the treatment of the A-pillar base and the way it intersects with the front fender and door shutline is but one example.

The interior references Parisian theatres with the use of plush red velvet on the rear lounge seat, contrasted with a masculine jet fighter driver's seat shell in silver. The accompanying rear-facing baby seat combines parts of both these elements, while the pedals are arranged in a clever ‘DS' logo: the Revolte has a role in introducing the new ‘DS' premium line too, by use of the amethyst, white and graphite body colors seen on the adjacent DS3 launched here too. Finally, check out the central screen in the IP that's supported on a web of red blood vessels that pulsate with light.

Watch this space for an in-depth Design Development article coming soon.

The Twizy is the smallest of Renault's four EV concepts. According to Patrick Lecharpy, VP of Advanced Design at Renault, it showcases two key aims: it defines a new design language around electric propulsion and yet still feels car-like - despite occupying a footprint only 2.3m long and 1.13m wide.

That Renault has largely achieved these goals is to the design team's great credit. The four wheels sit outboard of a central driver unit, framed by two outer rings. Doors bars, which recall the Smart Crossblade, pivot open from the end of the dashboard and do not fully enclose the driver compartment. They do, however, house the side airbags, contributing to the sense of security.

The face of the concept is formed from a large hexagonal display matrix, which is used not only for lighting and turn signals, but to communicate greetings and messages. The motif is repeated throughout the interior, with certain hexagonal forms, providing the driver with vehicle information through the use of rear-projection.

The interior is remarkable for its sense of space, born out of expansive glazing stretched over the driver's head and the open sides, but also the bulbous form of the IP that visually fades away at either side to increase the perceived width of the interior.

Of note is the lotus flower sitting atop the IP. Its petals close to inform the driver of remaining battery charge and vehicle range. It represents the design team's aims to find new ways of communicating to the driver, without creating anxiety.

The overall language of the vehicle arguably sits more within the realm of product design rather than traditional vehicle design, but for that it is no less successful. We will be intrigued to see how this concept translates into the production version Renault is promising for 2011.

Although the A5 Sportback is being shown for the first time at Frankfurt, the development program for this vehicle ran concurrently with the A5 coupe and cabriolet. Having worked on creating a design that feels like a true four-door coupe rather than a hatchback (which vehicles in this new segment are often unflatteringly compared to) the Sportback is a well-resolved addition to the range.

While the front of the vehicle and most of the interior are exactly the same as that seen on the A5 Coupe, the extra door, and increased length of the Sportback has been managed well. The beltline, which some designers consider lacks tension on the A5 coupe, is less pronounced here - the extra door and length of the Sportback helping to create a slightly less pronounced feel to the line.                                     

The surface resolution around the rear of the vehicle is particularly successful; the point where the base of the C-pillar meets with the broad shoulders and flows into the short deck lid is especially elegant. Note also the faint bone line, which begins in the A-pillar and runs over the top of the DLO, increasing in radius before bleeding into the rear deck surface. It runs parallel to the trunk-lid shut line and fades to nothing at the rear of the car.

Lending further credence to the impression of a premium coupe are the frameless doors and the tapering, coupe-like profile of the roofline. Although this compromises the rear headroom in the pair of rear seats, we suspect most Sportback buyers won't be unduly concerned. Elsewhere, the interior is the same as in the A5 coupe, and typical Audi attention to detail is apparent - note the cleverly split load cover, part of which stays in place and part of which lifts with the trunk lid, and the slivers of satin inlay highlights around the wood trim in the doors.