More Madison Avenue manipulation

Watching the Winter Olympics the other night I saw yet another manipulative advertisement, this time from Chevrolet.  Specifically for the Chevy Equinox model.  The ad boldly states as one of the reasons to buy the car that it gets 600 miles per tank.  I am certain that the intended implication is that the car is fuel efficient.  Yet the relevant measure of fuel efficiency is not miles per tank because tank sizes are not uniform.  The relevant measure is fuel cost per mile.  If you increase the size of the fuel tank you have not increased the fuel efficiency.

Jason