It's an interesting idea but i hope that you will use "elasticized" type of shirts.
I have seen lot of times shirts from games and seemed quite all a bit too much nerdy because stayed too wide on people wearing these.
It have to be cool if you want them to be used, imho.
P.S: i know that you now are making plain simple shirts, but imho shirt that would be very nice should be based (and designed on the entire surface) from some of these nice LFS race screenshots edited on photoshop like the one in the forum section, the ones that capture better the idea of speed