Chris,
Since you have been putting money in your wife's bank account to pay for the car finance, it will seem that she has been paying it instead of you. As the registered keeper, you do not have any legal rights on the car and you should consider taking your name off it because any speeding tickets/parking fines incurred by whoever is driving the car at the moment, will be sent to you.
If you can prove that you've been putting money in the bank for the purpose of paying the car finance, then you will stand a ground to win back the car but you will have to show proof that you've been putting money regularly (every month perhaps and a fixed sum to cover the loan payments). You should seek professional advice on this matter though.
