Garagebo effect

The perception that the performance of a vehicle has improved as the result of maintenance work at a garage that likely made no impact on the vehicle's actual functioning.

Most commonly experienced by people who have just paid for a questionable procedure a mechanic insisted was important and really want to believe that: a) the procedure was actually done; and b) it significantly helped the vehicle's performance.

Jon: Dude, that $1000 for a changing out my cabin filter and flushing my transmission was SO worth it! My Hyundai has never been this powerful...I could totally take a BMW off the line right now!!

Cameron: Really? Come on man, this is a classic case of the Garagebo effect! They probably waved a wrench over your crappy car and then gave it back to you and now you think you are Vin Diesel in Fast Five!