I think the EPA’s restrictions on diesels (in part to protect the hybrids’ turf and the interests of the ethanol lobby) are more to blame. Car buyers in their 40s or younger just don’t remember much about the GM diesel mess of the ‘80s. FWIW, I see a lot of younger drivers in VW TDI cars.
That may be a big part of the problem. Americans aren’t good at math and the price of diesel looks much bigger than gasoline on a gallon to gallon basis. They cannot extrapolate mentally the mpg differential and dollars per mile to any great effect..................