Sorry my computer had a PMS moment and sent the first reply before I was finished in error
Well guess you don't need another person to tell you to never leave George off leash. Yorkies have a high prey drive, and will take off at the sight of squirrels, birds, cats, even a fluttering leaf. As a rescue he could have ran off wanting to go back home. You were very lucky to have caught George. George wanting to run to the car may be from his past, maybe someone he liked very much used to come in a car to visit. I would be very careful on walks with George wanting to run up to cars, no retractable leash for now, walk on a 4 or 6 foot leash until he is fully bonded with you.
I agree with canana in working on commands, see what he already knows, if "stay" needs a firm tone, that's what you will have to use. 9 years old is "not" to old to teach new commands. If he is food motivated he will learn fast for that treat reward. Working on commands builds a bond with his owner, always high praise and treat rewards when he gets it right.
I have a rescue, he was 2 1/2 yo when I got him, we are a team for 4 years now and I am still leaning new things about him. I was very lucky, he bonded with me instantly. He is # 5 yorkie and none of my now passed girls were ever left off leash.
Don't give up on toys, although 9 year olds in my experience with my 4 girls played less with toys and more with me.
Please keep us updated on lil George, it is so tragic when these sweet lil babies are given away after so many years of living with one person.