1965-1966 Ford Mustang — MPG & Fuel Facts NO OFFICIAL EPA RATING

The EPA's public fuel-economy dataset only goes back to 1984 — the 1965-1966 Ford Mustang predates it, so there is no government-rated MPG number for this car anywhere, including here.

Estimated 12–21 MPG combined.

A 1964 Popular Mechanics nationwide owner survey (cited by Wikipedia) clocked a 260ci V8/automatic Mustang at 20.9 mpg holding a steady 60 mph; the lower end of the range comes from converging but non-period-tested owner-forum consensus for 289 4-barrel cars, so only the top of the range traces to an actual period test.

This is our estimate, not an EPA rating — built from the period road tests, marque-specialist guides and corroborated owner reports cited below, hedged where sources vary. Treat it as a ballpark for planning, not a spec to rely on.

First-generation Mustangs offered a 170ci or 200ci inline-six alongside 260ci and 289ci V8s in 2-barrel, 4-barrel, and high-performance 'HiPo' K-code tune, paired with 3-speed manual, 4-speed manual, or 3-speed Cruise-O-Matic automatic. That spread of engine states of tune and final-drive gearing is the main reason MPG estimates for this generation vary so widely between sources.

The one number that traces to an actual period document is a Popular Mechanics owner survey (Sept. 1964, 'Ford Mustangs -- how owners rate them,' pp. 81-85, 201), which Wikipedia's first-generation Mustang article cites for a steady-60-mph figure of 20.93 mpg on a 260 V8/automatic car. That is a real, page-numbered magazine citation, not a road test under load, so treat it as a best-case cruising number rather than a combined-driving average.

For the inline-six and 289 V8 (2-barrel and 4-barrel), no period magazine test with a printed MPG figure could be located. Multiple independent long-running enthusiast forum threads (Vintage Mustang Forums, AllFordMustangs, Grassroots Motorsports) converge on rough bands of ~12-18 mpg city / 18-26 mpg highway for the six and ~12-20 mpg for 289 V8 cars depending on carburetion and gearing -- consistent with each other but still owner-estimate, not measured-test data. One frequently repeated online claim of '38 mpg' for a six-cylinder automatic was explicitly challenged and rejected as unrealistic by experienced owners on Grassroots Motorsports.

Sources: Wikipedia, "Ford Mustang (first generation)" · Popular Mechanics, "Ford Mustangs -- how owners rate them" (Sept. 1964, via Google Books) · Grassroots Motorsports forum, "True, or BS? (Classic Mustang fuel economy)" · Vintage Mustang Forums, "1965 I6 fuel economy"

All classics Search Ford Mustang on FuelFacts (in case a later model year is in our 1984+ EPA data)