What might a Citroën C4 look like as a diesel hybrid with a hardtop cabrio roof? That fictional animal is reflected the C5 Airscape concept, PSA's entry in the Frankfurt auto show style sweepstakes. The concept moves the C5 upscale, with swank appointments from the Citroën design HQ, along with a showcase diesel-electric powertrain dubbed UrbanHybrid. It also hearkens the newly redesigned C5, slated to get a longer wheelbase and more upscale position. We'll see if that arrives in Frankfurt as well.