[cleanspeed1]

I wouldn't go that far, the manufacturers do it but unless you care heavily about it, you'll never know about it. I never looked in to the old school engines for mpg capability because, at the time, I never cared about it. But with all the complexity involved with modern engines, I find it hard to believe that prior to the advent of computer controls that the OEMs didn't have combinations that were fuel efficient, yet possibly limited because of the technology of the time.