Rationing is not going to happen unless there's truly not enough gas to go around, period. On the market, we'll purchase our oil at the expense of Namibia or Zimbabwe. Third world countries will be left out first. Sure, gas will be expensive (probably at least $4 here), but people will still pay. Some conservation can be done in the US; most people's driving is inelastic, as it consists of commuting to and from work in places where public transportation is non-existent. Carpooling may gain greater commonality, but I seriously doubt it would have any real effect on anything.
When/if rationing happens we will be in a depression, because when they start limiting people's gasoline consumption public sentiment will be in the toilet, not to mention their spending money and the job market.



