I've read several web sites which suggest that when selling a used car, you should ride along on the test drive with the prospective buyer.
This is better than handing off the keys to a total stranger who may just dissapear; or is it? That same stranger could drive you and the vehicle to a remote area and shoot you.
The only solution it seems is to get someone else you know to ride with you. But then we've got the buyer, his wife (probably their dog too), you and your buddy crammed into one vehicle. I can hear it now:
"It seems a little sluggish."
Then again, maybe he'll just off both you and your friend (bullets are cheap eh?). So, you'll just have to hire an ex Israeli special forces soldier to ride along.
There, I knew I'd find the answer if I though about it long enough. Now to Google some search terms "special forces" "bodygaurd" "hire".
Please post if you've ever been shot while riding along in a used car test drive.