Or you could get a RWD Mustang with more than 300 HP and 31mpg. That is about $25K less with decent options. Of course, if it has to be a hybrid, and it has to have more than 350hp... Interesting note on the M is that I think it will run in electric mode up to 60+ mph.
Personally I'm holding out for a Porsche Cayman w/T-top and the Toyota Prius HSD system. I fail to understand, completely, this new hybrid HP race. The Porsche Cayenne hybrid would be more attractive to me absent the forced induction.
Lexus GS450h has been rear wheel drive hybrid for a while now, and this hybrid M is a direct competitor. The Infiniti does get much better mileage. Its a very old hp race. The bmw activehybrid 5 should be the hp winner in this class. The mustang is quite different. I expect porsche to shart pumping out some hybrids soon, don't think on a t-top on a cayman? Now I know you don't want a porsche.