Its nothing that I have gone into researching.............its just something that I have heard as well. When I would get a new car it wasnt to save gas so I wouldnt check to see what my MPG was and when I bought this car (to save gas) it was used. I do remember there being some rumors about engine shavings and impurities in the oil for a new engine but I dont know if that affected MPG or if it is even true( again I dont care enough to go do some scientific research) to begin with. BTW do yoou have any info other than your experience that confirms that this "myth" is just that or do you just say this casually?