It isn't so much what you sell as where you sell it.

Grassroots lobbying groups and a relatively small number of politicians have been pushing the US government for more environmentally friendly measures to be put in place, particularly in the field of automotive travel. Vehicles in the US just aren't all that efficient, energy-wise, and on top of that, the most popular vehicles are SUVs and consumer Humvees that can be measured in dinosaurs per mile, and not miles per gallon. The hell of it is, there are much more efficient vehicles in use in Europe that get between 40 and 80 miles per gallon of fuel (averaged between city and country driving figures per model) - at the time the article was written, there are 113 of them, many manufactured by US automotive companies, but they can't be sold in the US because they don't quite match US diesel emissions specifications (which wouldn't be difficult to meet, I don't think, without a bit of work) and because the automotive unions refuse to let it happen because of the shakeup it would cause.