Third Party Car Insurance is a risk cover, under which the insurer compensates any legal liabilities claimed by the other party, in case the insured vehicle is at fault. However, as per the Motor Vehicles Act 1988, Section 146, plying an uninsured vehicle on Indian roads is an offence. This is why liability insurance is also known as ‘Act Only’ plan. This plan doesn’t cover the insured or his car.
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.
The Insurance Information Institute suggests that you take the amount you'd pay in one year for comprehensive and collision coverage, and multiply that number by 10. Is your car worth less than that number? Then comprehensive and collision coverage might not be a cost-effective option for you. In other words, you might want to talk to your agent about whether it makes sense to include these coverages on your car insurance policy.