He calls it the "Hyperloop" and he says it's better than a bullet train. The Hyperloop would get people to Los Angeles from San Francisco in 30 minutes.
However, he's been vague about how he's going to make the Hyperloop a reality.
The closest to detail he's gotten is when he said the Hyperloop is a "cross between a Concorde, a railgun and an air hockey table."
He's been so vague that it seems like what he's talking about can't possibly be real.