I notice on the visor there is a button to open the garage door. I have an electronic garage door but no opener for it (the side the car goes in anyway). Is there any remote units that I can buy to connect to it that will work with the car ?

 

Your garage door opener should have a small button intended for use when pairing the opener with a remote... in this case, your car. Find the section in your owner's manual about "Home Link", and follow the instructions.

Having done this recently with the G, one of my garage doors paired with the remote immediately (by syncing the remote to the visor.) But the other one wouldn't sync up to the remote, so I had to sync it to the opener itself.