1966-1980 Fiat 124 Spider / 128 — MPG & Fuel Facts NO OFFICIAL EPA RATING
The EPA's public fuel-economy dataset only goes back to 1984 — the 1966-1980 Fiat 124 Spider / 128 predates it, so there is no government-rated MPG number for this car anywhere, including here.
Estimated 19–31 MPG combined.
The EPA's own 1975 and 1978 Gas Mileage Guides rate the 128 at 20 city/28-31 highway and the 124 Spider (by then the 1.8L '1800' version) at 19 city/28 highway; a period British Motor magazine test of an early 128 recorded a close 22.9 mpg-US, corroborating the EPA figures.
The 128 (a small FWD economy sedan/wagon, sold in the U.S. into the late 1970s) and the 124 Spider (a RWD twin-cam roadster whose engine grew from 1.4L at its 1968 U.S. launch to 1.6L, then 1.8L by the mid-1970s, and eventually 2.0L for 1979-80) share a nameplate era here but are otherwise different cars with broadly similar four-cylinder economy.
EPA/FEA's 1975 Gas Mileage Guide lists the 128 (79 cu in / 1.3L four) at 20 city / 28 highway; the 1978 edition lists the same 1.3L 128 at 20 city / 31 highway (23 combined), and a 128 wagon variant at an identical 20/31.
The EPA's 1978 Gas Mileage Guide separately lists the '124 Sport' (Spider, by then fitted with the 1.8L / 107 cu in twin-cam) at 19 city / 28 highway (22 combined) - the only direct EPA-era figure we found for the Spider specifically.
Independently, Wikipedia's Fiat 128 article cites a period British 'Motor' magazine road test from April 1970 (shortly after the 128's UK launch) recording 27.5 mpg imperial (22.9 mpg US) - a period test result that lines up closely with the EPA's later 20-23 combined mpg for the same basic drivetrain.
Sources: EPA/FEA, 1975 Gas Mileage Guide for New Car Buyers, via Internet Archive · EPA, 1978 Gas Mileage Guide (2nd ed., Feb 1978), via Internet Archive · Wikipedia, "Fiat 128" (citing Motor magazine, April 1970)
All classicsSearch Fiat 124 Spider / 128 on FuelFacts (in case a later model year is in our 1984+ EPA data)