Once when I was 20 and another time when I was 23 or 24 I purchased cars from total strangers by putting money down, signing a contract and making payments. Both times it was about 75% down and the original owner, per the contract, wouldn't sign the title over until every [documented] dollar was paid. If the contract wasn't met due to my failure of payment, the contract stated the sellers would repo the car and issue no refund to me. Neither time were the sellers hosed on the deal. Good, honest buyers are out there, so don't give up hope on all of society!
It's the other 90% of the people we have to worry about.... You are rare these days... And thats pretty sad...