Steve,
That is like that friend of mine with the Cobra and 429 with two fours. I never did believe the gas mileage he said he got and one day we were coming home from Red Bluff and I was following him and I was really disgusted as I had to stay in 3rd and 4th gear to stay behind him. Even the school buss passed us and this is on the freeway with a 70 MPH limit. When we finally got to his house I asked him why he insisted on driving 45 to 55 MPH all the way home. He had his neighbor with him and they both said his speedometer was reading 80 MPH. I told him I now know how he gets that great gas mileage and he still wouldn't believe me, so there is a marked place on the freeway that is exactly 10 miles. We went and he drove that 10 miles and his speedometer registered around 18/22 miles I think it was. And he still hasn't changed that gear as he likes the great mileage.
Ron