I Pay a guy about $300 to Teflon my airplane once a year or so. It really looks great and holds up. The local Toyota/Lexus Dealer said it would be ok. The guy only want $125 for the car and said it would last a year easily.

Has anyone done this instead of waxing? If so, what was your experience?

Run...run away.

"Teflon" coating cannot be done with a wax-type product. There are plenty of products out there that claim to have "Teflon" but its a snake oil.

In order to be applied and have any effect Teflon needs to be baked on at over 600 degrees. I don't think you'd want to do that to a car...
What your guy is doing is waxing your plane...and your car. Thats all it is...