I have had Progressive for years and have never had any trouble. My car got plowed into by a deer, and Progressive was reasonable to deal with. Their rates are also about the best I can find. We bundle in our home insurance (through some licensed third party) and save even more! Our rates just actually went down this past 6-month period which was a pleasant surprise.
The cheapest car insurance, period, will likely carry the minimum coverage required in your state. In most states, this is liability insurance only, which covers property damage and medical bills for others due to accidents you cause. Some states also require uninsured and underinsured motorist coverage, which pay for your injuries or damage if an at-fault driver doesn’t have enough insurance.
Collision and comprehensive insurance are two optional types of auto insurance where your insurer pays for repairs to your vehicle. While there are other optional auto insurance coverages, liability, comprehensive, and collision are three of the most common. These coverages work hand-in-hand to repair or replace most of the damages to your car. It's important to know the difference, and make sure you're adequately covered.