In making a sale is it crucial to follow through, transferring the ownership of a vehicle into the state's computer system?

When I have sold a vehicle in the past, I have made it mandatory that I accompany the would be new owner to the county clerks office to make sure the transfer of title is documented on my states computer system. My uncle who was an attorney advised me to do this. However, all previous would be new owner's stated that, "ITS THE LAW", if the purchaser signs the back of the vehicle title, that I'm relieved of all liability regarding the vehicle being involved in an auto accident or used in a crime. I have even had car dealers argue that signing the back of the title relieves all liability. My state law may state this, I don't really know but, if the purchaser and my former vehicle are involved in a situation and the purchaser abandons the vehicle before the authorities arrive, wouldn't my vehicle sale be all hearsay? My previous purchasers have continued on to state that they will sign a bill of sale but, would that not be weak evidence? Couldn't an attorney still sue me if my name is still on my states computer system as the owner? Am I making too big a deal about this, its a lot of trouble arguing with these would be new owners?What is the best way to handle this transfer matter?