It's made out of what?

Citroën's new concept car, the Oli, is an answer to the hot question: How can the industry make electric vehicles affordable to the masses? The Oli is packed with solutions. But one in particular stands out. Citroën has devised a way to make the car's roof out of recycled corrugated cardboard. Working with BASF, Citroën created a honeycomb "sandwich structure" of cardboard between fiberglass reinforcing panels and coated in a polyurethane resin. The resulting lower-cost roof is half the weight of a comparable steel panel roof. And it's strong enough for an adult to stand on — or even to pitch a tent on, Citroën suggests.