Software used to design cars

Not sure it exists. I mean, sure, lots of 3D software exists that allows you to create 'class A', 'Degree 5+', 'curvature-continuous' nurbs surfaces. Some parametric, some not. Some $20k+, some < $1k. Some painful to use, and some a delight. I'm sure you can gather this much from a simple google search.

What comes to my mind though, is that these are all tools that allow a person to create things that are good, or things that kinda suck - like cars! I'm always amazed at the mypic perspective of folks (usually younger males) that can't get their minds off cars, and they'll spend their days sketching them, modelling them in 3D, etc. I think it's high time that these folks pull their heads out of their butts and recognize that car design isn't serving anyone other than their own childish egos. Really, I mean, yeah, I 'get' the notion of "mobile sculpture" - but that's kinda like calling the barrel of a tommy gun "elegant in it's simplicity".

My recommendation - don't use something that costs you so much that you then have to compromise your ethics (via toxic projects) to pay for. As has already been mentioned, there are open-source packages for both 2D and 3D. The windows version of Xara is good, fair, and doesn't force you to compromise your ideals (should you have them). And it's a total pleasure to use when compared with illustrator. Inkscape is a great open-source vector program that I have very limited experience with.
- 3D? I would recommend that you steer clear of software that is so closed that you need to pay ~ $2k/yr just to talk to the community who uses it. To get service releases, support - it's a trap, a nasty little trap that they placate you with the belief that it's the only software that can create such geometry/topology - absolute horse manure. As a student, you have lots of options - but again, look out for the traps - subscriptions/once you become pro, the price becomes 'ethics compromising', etc.
- If you're looking to do sculptural forms (i.e. cars if we were still in the 20th century), I'd say check out things like Alias (trap?), Rhino (good humans), Moi (good human), or anything that you can work with subD surfaces and get them into manufacturable data (i.e. modo, silo, etc.)