It may be against the law to drive without insurance, but more of your fellow drivers than you probably realize are driving without insurance. In fact, the Insurance Research Council says that the number of uninsured at-fault drivers in collisions is about one in seven, and if one of the six people with insurance is you, it's your wallet that will be tapped.

If an insured victim is in a collision with a driver who is both at-fault and uninsured, it is their insurance policy that will kick in, covering the expense of vehicle repairs, a rental car, and everything else. According to Carolyn Gorman, vice president of the Insurance Information Institute, "Despite the fact that you are the victim if an uninsured driver slams into your car, you are obligated to pay the deductible and your auto insurance will be used to cover repairs, as well as other expenses."

Uninsured motorists are not the only road hazard you may have to deal with, however. Underinsured drivers are also an issue. These are the people who carry nothing more than the minimum liability insurance required by their state of residence, and those minimums are not necessarily enough to compensate other people involved in their accidents.

The other driver's insurance, for example, won't cover a rental car while your own car is being repaired, but if your own policy has rental car coverage, you'll get one right away. It will be at your expense, but at least you won't be stuck without transportation.

While some states now require drivers to add uninsured motorist coverage to their policies, it is not required in every state. Be sure to read your policy and add this coverage if you don't already have it.