Make cars break down like they do irl. Let them deteriorate the higher mileage they are and make it cost money to repair them that requires a mechanic to RP it or anyone with knowledge on how to go about it. Introduce an upkeep or maintenance script for cars. The mileage doesn't have to be realistic obviously, but something reasonable with in-game driving habits. The higher the cost of the car, the higher the cost to repair it. Maybe that will make things more realistic and make people think twice about what they pay for cars and give them a reason to pay less than the previous owner did. I'm surprised nothing like this exists yet, honestly. Like some have said in this thread, there's enough millionaires in the economy in-game to pay a hefty price for cars second hand or not so leaving the problem to fix itself is non-existent unless somebody has another idea or there is an economy wipe which will make all statwhores go bonkers.