1968-1974 Plymouth Road Runner / Barracuda — MPG & Fuel Facts NO OFFICIAL EPA RATING

The EPA's public fuel-economy dataset only goes back to 1984 — the 1968-1974 Plymouth Road Runner / Barracuda predates it, so there is no government-rated MPG number for this car anywhere, including here.

Estimated 9–17 MPG combined.

A period Car Life test of a 1968 Road Runner 383 measured exactly '10 MPG,' and the U.S. government's own 1974 Gas Mileage Guide -- covering these same Chrysler platforms in its 'Plymouth Intermediate' (8.9-11.8 mpg, the Road Runner's Satellite-based platform) and 'Plymouth Compact' (12.5-16.7 mpg, the Barracuda's Valiant-based platform) categories -- brackets a similar range without naming the models individually.

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.

Road Runner ran 318ci up through 383ci, 440ci, and the 426ci Hemi; Barracuda (1968-74, including the 'Cuda) ran 318ci up through 340ci, 383ci, 440ci, and Hemi, both with manual or TorqueFlite automatic -- two related but distinct platforms (Road Runner on the mid-size B-body, Barracuda on the compact A/E-body) combined here as one nameplate group per the research brief.

Car Life's May 1968 road test of a base 383 Road Runner (reprinted with scans at Curbside Classic) states plainly '10 MPG fuel consumption' -- a real, quoted, period-tested figure for the model's signature engine. A related Car Life test of a 1968 Plymouth GTX convertible (a corporate B-body cousin with a 440) reported 11.9 mpg under test and 9-15 mpg in normal driving, corroborating the same rough band.

A genuinely useful supporting document: the U.S. EPA's own 1974 Gas Mileage Guide for Car Buyers (fetched directly as a PDF) tested MY1974 Chrysler products, listing 'Plymouth Intermediate' models (the Satellite/Road Runner platform) at 8.9-11.8 mpg and 'Plymouth Compact' models (the Valiant/Duster/Barracuda platform) at 12.5-16.7 mpg -- a real, primary, government-tested source, though it groups by platform class rather than naming Road Runner or Barracuda individually.

A separate claim of roughly 5-10 mpg for a 1970 Hemi 'Cuda, attributed to Hi-Performance Cars magazine via the same uncited secondary compilation used for the Charger entry, was not independently verified and is not used as a basis for the range here.

Sources: Car Life, 1968 road test, reprinted by Curbside Classic ("1968 Plymouth Road Runner 383") · U.S. EPA, "1974 Gas Mileage Guide for Car Buyers" (Feb. 1974)

All classics Search Plymouth Road Runner / Barracuda on FuelFacts (in case a later model year is in our 1984+ EPA data)