This week on The Best of Car Talk, here's a first. Ephraim went to the dealer to complain that his Audi's gas mileage was too good. Apparently, said gas mileage nearly doubled when Ephraim's fiancee began driving the Audi, so there must be something wrong with the car, right? As Tom and Ray would say, "Au contraire, piston puss!" Elsewhere, Rachel's mechanic warned her of "boulder intrusion" if she doesn't replace a broken CV boot; Pam's Toyota is dripping molten lead from the dashboard; and Al and his brother are arguing over whether it's possible to park a truck in a position from which it's impossible to move. Also, how one listener is using Car Talk to help teach English. Yes, really. All this and more, this week on the Best of Car Talk.