I've always wished for a network of rail flatbed cars that make high-speed runs from state to state.

You could drive onto one of the flatbeds (from a ramp) in your car, then ride the train from center-of-a-state to center-of-the-next-state. After a brief layover (for cars to get off and new ones to get on) the train would depart for the next state.

It just seems like a decent way to enable medium-speed, long-distance travel. And wherver you went, you'd have your car when you arrived.