Gina,
Welcome to RP! You have numerous problems.
Jack gave you the car which was owned, isnured and registered by him. He then gave you the signed title. Under NYS law, you had 14 days from that point to register/title and insure the vehicle. I may be wrong on this, but it sounds like you just kept driving/using it like nothing changed. I am not sure if you were listed on the actual insurance policy, but if not, it is actually insurance fraud in NY.
The car admittedly sounds like it was in your posession. I am not sure for how long. In NY City, in order for a car to be twoed, you must THREE unpaid parking tickets, all of which must be at least 90 dasy old. They are very good about snagging cars quickly these days. So if the car has been in your posession, it is very likely YOU got the tickets, and not him. Additionally, at the 90 day mark, a letter is sent to the registered owner.
If Jack gave you the title, and you properly registered such within the 14 days, you would have got a notice about the tickets.
To get that car out you need registration, insurance, fines paid up and a valid license.
-In God we trust. All others, put your hands on the car and don't move.