Question about buying Carter BBD for my 318 (unless I should look at something else)

I don't see 33 percent increase in economy with a square bore 4 barrel and an intake alone,, unless it's intake designed for a low end power and mileage like the Edelbrock Steetmaster318, , with a spread bore with small primaries, or a 400 CFM AFB would work well
JMO
I've collected parts to build a "gas mileage 273 when gas gets crazy $$, this intake and card will top the engine

16960833241118245963705228178212.jpg

16960833443974210202776252000714.jpg

16960875585185226119785150080049.jpg