1971-1973 Ford Mustang — MPG & Fuel Facts NO OFFICIAL EPA RATING
The EPA's public fuel-economy dataset only goes back to 1984 — the 1971-1973 Ford Mustang predates it, so there is no government-rated MPG number for this car anywhere, including here.
Estimated 8–18 MPG combined.
Car and Driver's February 1971 test of the Boss 351 measured just 7-8 mpg -- the one hard period figure for this generation -- while milder six-cylinder and small-V8 cars are only estimated in the mid-to-high teens by owner forums and modern aggregate data, since no period test of those configurations was located.
This generation grew significantly in size and weight versus the original Mustang and offered the widest engine spread of any Mustang era: a 250ci inline-six, 302ci and 351ci (Windsor and Cleveland) V8s, and a 429ci big-block V8 in the Boss 351 and other top trims. That spread is exactly why no single period-test range for the whole lineup exists.
The one figure that traces to an actual period road test is Car and Driver's February 1971 test of the Boss 351, widely quoted (via Curbside Classic's reprint of the original test) as returning '7 or 8 mpg' and leaving the reviewer 'in MPG shock' -- but that is the highest-state-of-tune 351 under hard driving, not a lineup-representative number.
No period magazine test or Hagerty/Hemmings buying-guide MPG statement could be confirmed for the milder 250 six, 302, or lower-output 351 configurations. Modern owner-logged data (Fuelly) shows roughly 10-12 mpg combined across mixed engines, and forum consensus estimates run higher (mid-teens to ~18-20) for six-cylinder and smaller-V8 cars driven gently -- directionally plausible but not period-verified.
Sources: Curbside Classic, "1971 Mustang Boss 351: Car & Driver And Motor Trend Wring Out The Fastest Classic Mustang" · Curbside Classic, "Vintage Reviews: 1971 Ford Mustang Boss 351" · Fuelly, 1971-1973 Ford Mustang owner-logged data
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