I would say it’s the 2009-11 STS-V with the 440hp Northstar. Also the somewhat unappreciated XTS-V sport with the 3.6 420hp twin turbo and awd. The CT-6 Blackwing as well. Apparently there are a few CT-6 models in various guises still on dealer lots. It’s the old, when GM gets it right and builds something exciting…