Beauty is in the eye of the beholder. It's to what you want out of a car. I had been for a while more focued on a car's performace and then it's styling, which in a way should be the other way around, though on another, function is more important than form. On another, form can follow function. It's what you want.
There are a lot of cars I like, oddly enough cars that perform well...
Such as the Corvette Z06 (C5), the BMW M3, M3CSL and the M5, also all the NSX's (espically the Acura/Honda 04 version, also the NSX-R), the Lancia Delta S4, the Austin Martin DB9 (well really the DBR9... I like race cars a ton... and the DBR9 is awesome even though it's not in GT4). The Nissan Skylines, namley the R32 and the R34.
Also the Lancer Evos, the Imprezas, the Mazda MX-5 Miata, the AE86 Levin, for various race cars, the C5R, the Viper GTS-R, just about every single Japan GT/FIAGTP/GT1/GTR/GTS/DTM/V8 Supercar/ etc car in there. They all look good.
That's my 2 cent's anywho, till later.