The gas guzzler tax doesn't really play a part in purchase decisions because almost no American brand car is subject to the tax. Heavy and powerful cars can get pretty good highway mileage with aerodynamics and a long overdrive gear, but their city mileage will be much lower, e.g. the 500hp Corvette Z06 gets 15mpg city/24 mpg hwy and pays no gas guzzler. The Pontiac G8, a heavier sedan with a 361hp V8, gets the same mileage. BTW minivans are also light trucks and exempt from gas guzzler.

I think CAFE did much more to discourage car sales vs. light trucks because minivans and SUVs counted towards the 21 mpg truck average instead of the 27 mpg car average. They were really boxed in to a certain product mix in order to meet the CAFE average, and small cars became their giveaway loss leaders, see Chevy Cavalier and Aveo.

I agree that the gas guzzler tax hasn't impacted many vehicles. However, the point of the law was that it was supposed to push efficiency and certainly not encourage SUV/light truck sales.

Regarding US CAFE standards, since 1975 (when CAFE standards began) European vehicles have accounted for fewer than 8% of US auto sales, but 100% of CAFE fines. No US or Asian auto maker has ever been fined under CAFE.

I don't think that CAFE standards in the past have done anything to improve US efficiency. CAFE standards have merely been a rubber stamping of easily attained US automaker efficiency.

Last week the US administration announced a supposedly tough new CAFE goal. However, a good description of this new US CAFE standard is that it (my bold emphasis):

"...simply allows the United States to match today’s European fleet efficiency (vehicles on the road now) some time after 2030." (NY Times/Lee Schipper)

An efficiency standard which is at least 20 years behind currently available technology is no standard at all.