Comprehensive car insurance covers damages from an "act of God," or events that are not caused by a car driving into something else. An "act of God" can include things like damage from a heavy tree branch falling on your car. Since you have no control over when or why a tree branch would fall on your car, this kind of accident would be covered under your comprehensive policy.

Insurance terms, definitions and explanations are intended for informational purposes only and do not in any way replace or modify the definitions and information contained in individual insurance contracts, policies or declaration pages, which control coverage determinations. Such terms may vary by state, and exclusions may apply. Discounts may not be applied to all policy coverages.
To help you figure out if you should purchase collision coverage, you should estimate the approximate value of your vehicle. While there are a number of online resources that can help with this, including Kelley Blue Book, we recommend you speak with a State Farm® agent. In addition to helping you determine the value of your vehicle, our agents can tell you how much extra you'd pay to add collision coverage.
1The Banking Benefits – Deposit Introductory program offers a high yield fixed Introductory Rate during the first 12 statement cycles after opening a new Consumer Money Market Savings account with State Farm Bank. A new Consumer Money Market Savings account means you cannot have an existing Money Market Savings with the same ownership currently open or which closed within the last 12 months. Your Benefit account balance must remain below $5,000,000 to earn the Introductory Rate. If the account balance is $5,000,000 or above, you will earn the Standard Rate on your entire balance. The new Money Market Savings must be a Personal or Trust account. IRA Money Market, Estate, Uniform Transfer to Minors, and Business accounts are NOT eligible.

There is a case to be made for getting just comprehensive and not collision insurance, even if your car is not valuable. Comprehensive covers you for a lot more perils than does collision--including, most importantly, against theft. Regardless of the value of your car, having it stolen is a major inconvenience. Even if your car is worth only $2,000 at the time of the theft, and your insurer gives you $1,500, that sum would go a long way in buying yourself a new vehicle. As we discuss in more detail below, comprehensive insurance generally costs no more than $200 per year, so a $1,500 reimbursement would make the coverage valuable.
Insurers don't determine your actual cash value (ACV) settlement based on what you owe, but rather on what the car is worth just prior to the accident. Let's say you owe $20,000 on your new car, but it's only worth about $16,000. If your car is totaled, you might get a settlement check of $16,000 but still owe an additional $4,000 on your loan or lease.