My brother and I got a car for my mom like right after my parents started divorce proceedings 5 years ago. It was good for a couple years but then started getting to the point that we would constantly take her on test drives of other cars. We saw the perfect little Acura with radar/lane-keeping everything and convinced her that for Mother's Day, she should let us trade-in the old, tired Lexus as the down payment for it.
A 1/4 mile from the dealership, the transmission had a catastrophic failure and slipped like I've never seen while going up a hill. I had to reverse 50 yards down a busy street and take a less hilly path around to the dealership. I never got it to exceed 20 mph and I rolled through every single stop sign to maintain momentum. When I coasted into the parking lot, I cleared the check engine lights for the final time using my OBD2 scanner.
I am so thankful they did not drive that car around to appraise it. We clenched for 8 hours haggling the way you would expect Persians and Philipinos to do and then we took the offer and ran.
We also got her perfumes and chocolates, but this was so much better.