There are quite a few cars for sale outside the US which do well on fuel efficiency so one might be able to phase in the standard fairly quickly.

Where I live, older vehicles that can no longer pass their emissions tests and are too expensive to fix get junked though there are some exceptions. In some sense, that forces older cars off the road.

Again, CAFE can help, but our basic problem is a fuel shortage and we need to address that with imediate conservation since it is quite clear that market forces cannot alleviate the shortage, only ration by price. The considered drill won't do anything really to help considering general depletion. In shortage situations, we use our rationing plan and that is what will drive our conservation effort. It also assures us that we will have the money available to buy efficient cars that can re-exend our range of mobility.

Chris

Hi Name,
This is an important issue, as improving vehicle mpg is going to be one of the major drivers of reducing oil consumption. The article posted by Stuart Staniford at TOD on 11th Feb, 2007 examines this in detail.
You are correct that we cannot immediately improve the CAFE standards, but last year as well as the 7million passenger vehicles(average 27mpg) there were 7million light trucks and SUV's sold in US, having an average of 22mpg. Fuel efficiency for ALL new vehicles could be raised by phasing out the lowest fuel economy vehicles, AND raising CAFE standards for ALL vehicles in a progressive, but more aggressive manner than currently proposed . The US has one of the poorest fuel economy fleets. High fuel prices cause people to use low mpg vehicles less (since the average household has 2.2 vehicles some options are available for many households).
New vehicles 6 years old or less, are responsible for 50% all ALL VMT, so a rapid improvement in fleet average mpg will give much bigger savings than you projected above.

The argument that if there is a recession, less vehicles will be sold,so can't have much effect on efficiency doesn't hold up, since in the 1978-82 recession US average fuel consumption for VMT decreased, due partly to a very big increase( for the next decade) in new vehicle efficiency.