Increased MPG for carbs?

[C-10 simplex]

It's getting a little late night for me to get into it whole-hog. But here is what i DON'T believe in:

The whole notion about cold air intakes increases mpg. Why? Because warmer air=less dense air= less fuel. Leave the stock air cleaner assembly completely hooked up the way it came from the factory for best mpg results. Also, what many people may not realize is at full throttle---when vacuum is low, the stock air cleaner lets nothing BUT cold air to the carb.

Discuss.