State-Mandated Health Care Unconstitutional, But What about Car-Insurance?

The recent declaration of Obamacare, specifically the section that mandates the uninsured to buy health insurance, unconstitutional is a victory for liberty and a reason for celebration.

But one thing I never understood, and I haven't understood this since I was sixteen and one month, was why I have to purchase state-mandated car insurance.

What if I can't afford to drive and pay for insurance and pay for gas that is continually going up in price? How does one save when a teenager?

Having a car assumes someone has saved enough for car payments and gas to use the contraption. That is understood. But this law has the potential to kill savings, if it has not already done so, and is a way to force young people, even the responsible ones, to quit driving all together. At least that's what I think.

Can someone please tell me the difference between state-mandated health insurance and state-mandated car insurance? Somebody? Anybody?

I must look deeper into the history and reasoning behind state-mandated car insurance.