The new Buick Rivera concept. Designed by GM's Shanghai division, it's not American design, but it's absolutely beautiful. Not an Aston Martin, but beautiful nonetheless. This could complete with the Mercedes and BMW midline offerings easily, if they could build it with good fit and finish, even if the gullwing doors don't make it to production.
GM, please... let this come to fruition, with as few changes as possible. It is doable. You could sell these and make a tidy profit off of them. Power it with the LS3 or LS7 motor with matching transmission, sell them for $80k, and make those of us who think that we can do better than we are proud.