I dont think the rear gas cap is bad at all. It would look horribly out of place if they made it chrome/silver but the black blends in and fills up the rear decklid without being too in your face.
Ok I fixed my post with a new table I created that has all the right numbers... got a mod to fix the specs thread too. You are right, the rear legroom is actually 0.8" more.
Here is the comparison from this thread: http://www.mustang6g.com/forums/showthread.php/2015-mustang-s550-986.html
Front legroom got a 2.1" increase and rear legroom got a 0.8" increase.
It's really impossible to notice these differences in pictures, I cant wait to actually get to...