Turbo charging off topic

Hello,
I am posting here because this is Somewhat off topic.
I got into a debate of sorts on another site , not mopar related, and i asked if a person were to build two identical cars, same engine, same driving style, etc, Only difference between the cars was one is turbocharged, and the other normally aspirated (fuel injected) would the turbo car be more efficient? Better gas mileage?
I got two replies that were almost hostile stating that "if i could not achieve 50 mpg in a saturn automobile i must be doing something wrong", and "that there has never been any documented proof that turbocharging is more efficient"
They both agreed that more air requires more fuel and therefore = less gas mileage
Am i off base here? I know folks turbocharge for more power, but could one also achieve a thrifty commuter if that was the goal?
Set me straight.
Russ