Audi and BMW with carbon fibers

BMW just yesterday began production of its carbon-fiber-bodied i3—a vehicle that makes some major advances in the way lightweight, mass-produced vehicles are made.Reports from earlier in the year suggest that the next-generation Audi Q7 due next year might be employing some of those techniques
But for now, BMW appears to be going it alone. For Audi, which was a leader in the development of aluminum-bodied cars 20 years ago with the original Audi A8, the future will follow a more diversified approach, according to a key executive.

The reasons? Price is one; so is the rate at which you can produce a carbon-fiber vehicle.
“To make an area of a car in carbon fiber is very expensive,” said Dr. Ulrich Hackenberg, the Audi AG board member in charge of technical development, last week at a Frankfurt Motor Show roundtable. “We are looking at the cost aspects and the aspects of strength as a starting point.”
Hinting at what materials we're likely to see in future Audi models to reduce weight, Hackenberg explained that flexibility is crucial and that using different materials in different places in a car might be the way to do it. For instance, high-strength steel could provide safety protection around the A-pillar, while an aluminum space frame could underpin the vehicle and surfaces could be done in laminated steel, plastics, or carbon fiber.
Flexibility is crucial, and using different materials in different places might be the way to do it.“I think you need the right material at the right place in the car, and the challenge is how to bring it together,” said Hackenberg. “You need different machinery, different robots, and everything to do that.”