It's pretty good though, 21/30 I think? I can understand the subjective preference for the ST/Speed3 for some folks, but that 3.7 with the 6spd is crazy fast for the price. To really get the nutty ~5 second 0-60 and nearly 1G grip you have to get the upgraded package though, and they seem fairly rare on dealer lots, as well as marked up a bit. I found one I really liked, and it was close to $30k sticker! I think it's somewhat of a hidden gem. The muscle car purists don't like it much due to no V8 monster torque, but it's a very legit sports car with the numbers on pace with much more expensive/reputable competition. Probably a lot of the impact would be lost if paired with an automatic, but with the manual and the approach of driving it like a V6 sports car (think Z/etc), it's ludicrously good value. It's fairly large, but drives like a perceived smaller car. The 370Z base coupe is 3,245lbs, the Mustang V6 Premium slots in at 3,450. This compares well to WRX @ 3370lbs, Speed3 @ 3280lbs, and Focus ST @ 3223lbs, when you consider the 305hp/280tq powerplant. IOW, the Mustang V6 is fairly close weight to the i4 turbo crowd, while having a bit more performance. The FRS/BRZ are a different animal altogether, tons less weight, and tons less power, and that can be good/bad depending on application and preference.
Honestly it's win/win with all of these great cars in the sub $30k range. The Mustang V6 wasn't even a valid option until very recently. Not even valid, it was unthinkable.