People remember the auto-destruct diesels that GM built back in the 80s, and they think that diesel cars still smell like a city bus.
I think most American drivers now associate diesel with the German marques, but don't ponder the issue much beyond the prices they see posted at the filling stations.
There's one guy I see almost every week, pumping E85 into a late-'90s vintage Honda Accord. He doesn't know or care that his car wasn't built to take the stuff - it's just the cheapest fuel he can find.
I did see premium unleaded priced higher than diesel recently. That may have been the first time in over a decade I'd noticed that.