Typically you can add a vehicle to a policy, such as your spouse's car insurance policy, by an endorsement.

An endorsement is a document which is attached to the policy that modifies or changes the original policy in some way. You will need to let your wife's insurance company know your mother is also listed on the title. Insurance companies' guidelines when there is someone else on the title/registration vary.

Some insurance companies may require you to remove your mother from the registration. Other companies will allow her name to remain on the registration and will ignore your mother as co-owner entirely. Still, other companies will allow her name to remain on the registration and give you a choice. They will tell you to either list her as an additional driver on the policy. Or, they will tell you to specifically exclude her from the policy. If you have to list her, and you choose to exclude her, the insurance company will probably have an extra form for you to sign.

If adding a vehicle to your wife's policy does not reflect in a multi-car discount auto insurance premium, then get a quote at CarInsurance.com.