Can I add my son's girlfriends car to my auto insurance policy?

Yes, you can as long as she lives with you in the same household. One thing to keep in mind that people don't realize when adding young drivers is that your policy premium will go up and at any time they get into an accident or get a ticket your premium will go up due to their negligence but as soon as they get their own insurance the incident will follow them and not effect your policy anymore. The reason the insurance may be cheaper with adding her onto your policy opposed to her having her own policy is because the risk is spread over however many people are on the policy instead of just her. For example, if you have a solid clear driving history the chance of you getting involved in an incident is a lot less then her, so the insurance company won't have to charge as much because there is a chance you might drive the vehicle since it is at your residence and she lives with you. If she doesn't live with you, it might be an issue. You will have to check with your insurance company about garaging locations if thats the case. Hope it helps.

I think she can but maybe she can't, ask her insurers, they'll know more than me. RE: Can my grandmother add my car to her auto insurance policy? I have a car that'm a 19 year old male, if that makes any difference.

Why would you do that? Girlfriends come and go. If she is unable to afford car insurance perhaps HER parents should be the ones to help her out, that is unless you don't mind paying the dramatically increased rates of having a teen driver on your policy.

Sorry, I've no idea about this

Very Bad Idea!!! You are just asking for problems! Her cost is not your problem!

thanks to each and everyone of you for the replies!