Eventually, there's no good reason (other than economics) why car manufacturers couldn't go to a full HUD (heads-up-display), similar to what's found on military aircraft. A small projector and CPU could be embedded in the dash and project up on the windshield...hell, there are technologies in the works now for clear semiconductors, allowing the display to be right in the windshield itself.
If you were enterprising enough, I'm sure you could homebrew something with a DLP chip and a projector, linking it to a vehicle's onboard computer or a GPS unit. Real time speed, heading, altitude, even what that pesky "Check Engine" light meant if you had it interfaced to the OBD processor. Having it linked to a controller on the steering wheel would be the ultimate, you could flip through menus without ever having your eyes leave the road in front of you.