It is not true that price independantly influences demand. If gas went from 1 cent/gallon to 2 cents/gallon, would people behave differently? The elasticity of deamand is the concept here, how long will it take people to change there long-term behavior because of a price change? So far prices have not gone high enough for long enough to make large changes.
The second thing to look at is the negative externalities of gas consumption. Why can I make a claim to have footing to curtail your consumption? Because you don't pay the true costs of your gas consumption. I/we/the world does.
When you buy gas you do not pay for:
-The health issues resulting from its use
-The environmental issues resulting from its use
-The costs of technological research to figure out
what to do when it is gone.
-To some extent, the wars/polotics associated with it
-The costs of droughts/famines, etc. related to global warming
-And it goes on....
If gas costs what it really costs, and people paid that much, then they may have a fair argument for unhindered consumption. Currently that is not the case.
-Lightweight materials are not more expensice btw. I have an aluminum car that will NEVER rust up here in MN. It should last as long at maybe 3 steel cars, the savings are clear.