Gadgets Don’t Cut Fuel Bills—Performance Upgrades Do

Project Farm tested fuel-saving gadgets and found they don’t deliver real savings; gains came from performance mods that improve airflow (high-flow exhaust, cold-air intake) plus ECU tuning, and later from driving behavior (lower speeds, proper tire inflation). Baseline 17.06 mpg on a 319k-mile Suburban rose to 18.78 mpg with about $974 in mods, and peaked at 20.39 mpg with driving changes. At ~$4.50/gal, it would take tens of thousands of miles to recoup the investment, meaning the biggest payoffs come from careful driving and proper maintenance rather than gimmicks.