[jcl]

If you assume the problem is "Where will we find energy to sustain our current consumption rate?", then you're right: air-cars aren't a solution. Such a solution might not even exist.

But if you assume the problem is "How can we relieve market pressure on our most constrained resource?", air and electric cars are a solution. The hope is that by diversifying the sources of energy used for transportation, we can continue to use oil for other purposes that we haven't found cost-effective replacements for yet -- like plastics and jet fuel.

So while the cars won't solve the energy crisis by themselves, maybe they'll buy us enough time to reach the "then a miracle occurs" discovery that does solve it. Or, failing that, maybe they'll help civilization make a slow transition to reduced consumption, rather than a sharp crash.

[khafra]

Materials science needs to get on the ball and invent Adamantium, from Marvel Comics. Then we can have compressed air-powered airliners.