I don't know if the students finding the data discrepancies that exposed VW's operation looked at other cars, but in US VW is the only company selling diesel cars in volume. There are a handful of BMW and Mercedes models and one Chevy, but VW is the only big seller.

But that's still nothing compared to sales of diesel pickup trucks, many of which have software installed to dump fuel and spit out dark clouds of soot because it looks tough.