General Motors Company [NYSE:GM] has built a fully-drivable version of its 2005 Sequel concept car, CEO Richard Wagoner revealed recently. The crossover has a range of 300 miles and will be officially unveiled next month.

Despite this, Wagoner claims a production model of the car is still some way off.

"That's rocket science when you get in that car," he said. "This is the most sophisticated product, technologically advanced product, I think we've ever made in the history of GM."