According to this speech by the Chairman of the National Petroleum Council it takes 18 years to turn over the US vehicle fleet. My understanding is that the average age of cars on the road is around ten years (Correct?) and that there’s something like 200 million cars on the road (Again, correct?). Now, according to this NPR piece, the US fleet of cars produces some 3 to 5% of global greenhouse gases. So, what’s the big issue about getting cars to have fewer greenhouse gas emissions? Obviously it’s a good idea to get them lower, but cars can’t be the single largest source of greenhouse gases, can they?
If they’re not, what is? If they are, then what’s the next closest source in terms of percentage?
US EIA Greenhouse Gas Inventory Report.
http://www.eia.doe.gov/oiaf/1605/ggrpt/index.html
You probably want Sections 1 or 2.
Part of the big deal is that transportation (cars, trucks, buses, aircraft, trains, ships, etc.) are responsible for about 1/3 of the US greenhouse gas emissions, and a big chunk of that is passenger cars. A second part of the big deal is that the US wants to remain an auto manufacturer, and since most of the rest of the car-driving world is moving toward more fuel efficient and lower GHG emitting vehicles, it would be wise for the US to do the same thing. There is also a bit of the “you first - no, *you * first” thing going on globally. China and India are going to be huge CO2 emitters, and it’ll be that much harder to convince them to move as rapidly as possible to the most CO2-efficient vehicles if they see we’re not doing the same thing.