Buying insurance is a personal choice but the normal mantra is to buy as much as you can afford. So the amount of insurance that should be bought for your son's vehicle is the amount you and him will be comfortable having on it.

Liability insurance typically includes bodily injury and property damage and is normally what is required according to most state financial responsibility laws.

Bodily injury liability insurance covers people's bodily injuries or death for which a driver on the policy is responsible for. Claims for bodily injury may include medical bills, loss of income or pain and suffering to those that you as a driver hurt when at fault in an accident. You will want enough BI insurance to over a judgment against you in a lawsuit without putting your personal assets at risk.

Property damage liability covers you if your car damages someone else's property. Usually it will be a person's car but it could also be a fence, house, etc. It is suggested to buy as much PD coverage as possible to cover the amount of damage your car might make to another vehicle or object.

Liability insurance only covers injuries or property damages that you cause others and does not cover you or your own vehicle. To have coverage on your own vehicle you need physical damage coverage of comprehensive and/or collision. When you have both comp. and collision it can be termed full coverage.

Comprehensive covers your car from losses resulting from incidents other than collision. This includes things such as theft, fire and vandalism. Collision covers damage to your car when your car hits, or is hit by, another vehicle or object.

Physical damage coverages come with a deductible of your choosing at the inception of the policy. For older vehicles, one might consider dropping PD coverage since coverage is usually limited to the cash value of the car.

If the car is older than there might not be a downside to going with liability only. But if you and your son want insurance on the vehicle to pay for damages to the vehicle if he is at fault in an accident or if it is stolen, than having collision and comprehensive on the vehicle may be worth paying the extra amount.

If you want to continue comparison shopping for car insurance you can do so here.