Nice car considering he lived in one of the cheaper university owned apartments. Rent around $500/mo (bills inclusive) divided by 2 roomates = $250. There has also been mention of about 3 middle-eastern looking roomies bringing the rent down even more. The link to these diversified (university site description) apartments are in a recent post on this thread.
The Lincoln Town Car is an '88 model. It could be he was driving it just because 17 year old gas guzzlers (V8) are cheap to buy. I ran the VIN through CarFax (free version) to get the year and motor. They don't give previous owner information because of privacy laws, but will give where the car has been registered before with the paid version of CarFax.
Maybe someone with connections at an Oklahoma Tag Agency could find out who owned the car before Hinrichs.