You don't need to be in engineering to be part of the team (at least this is the policy my university has). You don't get credits for the work and effort you put into it. You just get satisfaction that you contributed to an awesome racecar. It's also nice to have it on your resume, but I wouldn't do it for that reason, it's just a perk.
We had a physics student, a business student, even an arts student on our team. You just have to be passionate about cars and want to help out.
Any engineering program is going to have a lot of math involved, especially mechanical. I took computer engineering (actually, most of our team was in the same program as me).
