I totally agree with you on the first point... on the second point, I really don't think you can limit this to Americans. I think there are plenty of crappy drivers the world around. In general, I believe there are fewer automobile deaths (as a percentage of total mileage driven) in the U.S. than in most other countries. The reason we have so many accidents in total is because we drive so much compared to other countries, where gas and cars are more expensive... plus the U.S. is a huge country. But I think the percentage of crappy drivers will be pretty much the same in most modern countries.

The question here shouldn't be about pollution per gallon, but rather pollution per mile. Even if gasoline produces fewer combustion pollutants per gallon, gas engines are typically less efficient and hence require more gallons to go the same distance as a diesel engine. Thus, the relevant question is whether the gas or the diesel engine produces more pollutants per distance driven. Even in this case, gas may ultimately be less polluting, but only if the manufacturers actually implement better pollution control, which in this country doesn't seem to be likely anytime soon.