I have to say my family has been a huge vw buyer over the years....I or my parents have owned at least 13 VW's...my last jetta had 260K miles and was on the original clutch. I have always been a fan of German engineering (well....except for my pickups and SUV's which have been GM for the most part).
I really am wondering if VW is the only car company that did this. I have to believe that car companies all know what the others are doing....they all reverse engineer each others cars so I find it highly unlikely that VW is alone in having software that defeated emissions testing. And I will go further and put in my conspiracy hat...the Obama administration won't hammer American automakers because the penalties would be too high....they won't hammer Toyota who make the Prius which fits into Obama's Global Warming BS... .so it leads to a European manufacturer (and Obama hates white Europeans anyway) so VW becomes the fall guy.
Let's face it, it's not like VW had mileage that was 50% better than everyone else. Their mileage was right about where the other car companies were. But most don't make diesels. Now when you compare the diesel Jetta's and Golf's they sell in Europe they get about 30% better mileage than the versions here in the US due to the emissions crap we have to put on them so I don't doubt that VW put some enhancements in the software....I just doubt very much that they were the only company doing this. Just my $0.02.