I drive a 2003 Mazda 6. In the summer of 2005 and 2007 I was driving my car at an altitude higher than my normal Kansas altitude and experienced vapor lock. (just outside Limon, CO and Cheyenne, WY) The guy who towed my car in 2005 recommended a little diesel (1 cup per tank)to remedy the problem. My husband suggests also using premium gasoline. I have the oil changed regularly and never use ethanol blends. I'm about to head out again this summer to Wyoming. Have you heard of vapor lock in a new car like this? And have you heard of this solution? THe premium gas and diesel did seem to resolve the problem.