School loan interest rates?

Why can I get an interest rate on a car loan that is so much less than my student loans? School loans go toward college allowing for a better paying job to pay more in taxes, and along with a high interest rate of 6 - 6.8%, pay more on the money I borrowed. And every year tuition increases furthering this dependency. College is an investment not only for me, but for the nation itself. It's going to hit a point where going to college isn't a financially wise decision.