A reader writes:
You asked, "Is this really a wise use of tax dollars?"
The problem with advanced research is that not every goal is necessarily important just because of the goal, but because what's created on the route to the goal.
For instance, it was an amazing foreign policy coup to go to the moon, but even without that incentive it still would have been worth it. Not because of the benefit of having some moon rocks, and not because of the joy of seeing two people bounce around in low gravity, but because the incredible technological feats that needed to be performed to get there. We went to space, and along the way we got Velcro and a hundred other inventions. We wanted to crack the Enigma code, and we got the modern computer. DARPA wanted information networks that could withstand a nuclear attack, and we got the internet.
Are we going to have flying cars? Probably not. But I bet you that some of that technology is going to make commercial flying cheaper or more economically efficient (the car will need to be very light and get a lot out of what little fuel it can carry). It might lead to new materials, or better auto-piloting software. Or we might get some random new gadget, purely by accident.
I can't imagine a more awesome use for tax dollars! Who the hell cares about roads, BECAUSE WE HAVE FLYING HUMVEES, BITCHES!