Here is my attempt. I prefer simple shirts, I don't like shirts with pics of cars all over them. Makes me feel like its a Walmart NASCAR shirt.

I think it would be cool to get the 5.0 in whatever color your car is. Not sure how hard or pricey that would be. And for different colors perhaps do the font in white, or whatever contrasting color you want.
Version 1 front
Version 1 back
Version 2 front
Version 2 back
Version 3 would be the same as version 2 just with the running pony on the left sleeve. Maybe on Version 2 get the 5.0 in the correct font from the badge on the left sleeve.