Not just the eco cops, but every alphabet soup agency may be putting a jack boot on VW's throat. In addition to EPA and DOJ, FTC can, and should, hammer them for a blatantly long running campaign of false and misleading advertising, and IRS may, and should, get the tax credit money back.
Maybe this will just be a speed bump for them, but they're an insignificant player in this country, and this could drive them out of business here.
Edit: And that's just the Feds. Who thinks the states won't be lining up for free money?