if i were to go on a coast to coast road trip with my brand shiny new C7, with the 7-speed MT (actually mine is AT), and had to maintain, say, 50 mph, im guessing that conventional wisdom would suggest that i would get the max gas mileage in 7th gear. and i would agree that in a vacuum (ceteris paribus), this might be the case--notwithstanding the fact that due to lack of oxygen, you car would not start. however, in a typical environment would 7th speed give you optimal fuel mileage? i think not. if im right, how would you determine at various speeds, what the most fuel efficient gear would be? apologies if by posting this query, im living up to my chosen internet name--i do that from time to time, totally unintentionally.