Actually, there still may be hope for this one.
City cars have never been immensely popular in the US. There's the Fiat 500, and, well, that's about it. Even the Ford Fiesta is bigger. The Scion iQ was a disaster and the Mini Cooper is no longer all that mini. Still, if a new city car with the right formula were to come along, there's a decent enough chance it could catch on in the US, especially with Millennials. The Opel Adam, launched in 2012, could just be that car.
With a choice of three small, but powerful enough, gasoline engines and a five-speed manual gearbox, the Opel Adam is a three-door hatchback that can be customized ad nauseum. There are supposedly no less than 61,000 combination possibilities for the exterior and over 82,000 for the interior. If the Opel Adam were to be shipped stateside, it's possible it'll be sold as a Buick. Obviously this is all speculative, but GM is watching the American market carefully on this one. There could be money to be made here.