Many companies advertise that they can save you up to 15% off of your auto insurance. The truth is that they are not alone. Most companies offer discounts that will help reduce your auto premiums. Here are just a few:

Low Mileage Discount (this may vary depending upon your mileage)
Good student discount 
Student away from home discount
Over 65 discount
Multi-Car discount
Home and Auto with the same company discount
Auto Club discounts

There may be other discounts as well. Keep in mind that while you may want to get the lowest premiums possible, do not let it be at the expense of good coverage. The reason for having auto insurance is to protect you should there be a claim, so don't skimp on your coverages. After the accident, its too late.