Just my $.02-make sure you're interested in auto design and not just tinkering/modifying. Also take advantage of the variety available in college and explore as many different areas of engineering as possible while you have the opportunity. There are alot of fascinating areas of engineering and in my experience an interest/hobby doesn't necessarily translate into a fulfilling career. The auto industry is tough too, especially if you go work for an OEM.
I'm a gearhead through and through and have a M.S. in ME with a focus on materials, mainly composites and structural adhesives. I did FSAE for a year and interned at the GM proving grounds in Milford, MI, and my M.S. research project was funded by GM and focused on some new composites they were looking into for body panels etc. While I enjoyed all of it, I eventually realized I'd rather do something different and work on cars in my spare time. I'm an engineering project manager at an electronics company now and couldn't be happier. I'm doing something I enjoy and have time and cash to tinker at night and on weekends. Just gotta find what works for you!