ZL1 is a better car. More comfortable. Faster.
GT350R is very special. And I can totally see them picking. I've said it before, the GT350/R is the only mustang to date I would actually buy. It's a dream car for people that hate ford as much as it is for people who don't (IMO).
That said, the GT350R should be compared to the ZL1 1LE.
GT350 should be compared to the ZL1 non 1LE.
The GT350R has very little to no interior options, rougher and stiffer as noted with 315 SC2s all around with Carbon fiber wheels...That's race car stuff. Now, the ZL1 1LE is the same thing. Bigger/better brakes, bigger better stickier tires, an air foil, stiffer track focused suspension. But it still races at full ZL1 weight. Had they had a 1LE, it would have been a murder in the speed category.
I don't care they selected the GT350R really, in my book, the ZL1 won as I appreciate a comfortable relaxed car that still goes out and beats cars that aren't comfortable and are meant to race.
