Ford CEO Jim Farley teased this week that an all-electric Bronco could be on the way in the coming years, but the gasoline-powered versions going on sale this summer aren’t exactly the greenest machines.

The Ford-backed Bronco Nation forum has released official fuel economy numbers for the upcoming 4x4 SUV and they’re pretty much what you’d expect from a powerful truck shaped like a box.

The 2021 Ford Bronco

The 2021 Ford Bronco

The figures vary depending on the trim and tire size, but top out at 20 mpg city, 22 mpg highway and 21 mpg combined for models powered by the 300 hp 2.3-liter turbocharged four-cylinder engine equipped with either a 7-speed manual or 10-speed automatic transmission. The 330 hp 2.7-liter turbocharged V6, which is only available with the automatic, fared slightly worse at 18/20/19 mpg.

A Ford spokesman told Fox News Autos that the ratings apply to both two-door and four-door models.

THE 2021 FORD BRONCO IS MORE POWERFUL THAN EXPECTED

The larger Ford Ranger 4x4 pickup using the same 2.3-liter powertrain as the Bronco, but tuned to 270 hp, is rated at 20/24/22 mpg. However, the two-door Jeep Wrangler, which is available with either a 2.0-liter turbocharged four-cylinder rated at 270 hp and a maximum of 22/24/23 mpg or a 285 hp 3.6-liter naturally-aspirated that delivers up to 20/24/21 mpg, both paired to automatic transmissions, offers a more direct comparison. Four-door Wrangler models check-in at 21/24/22 mpg and 19/24/21, respectively, and the models equipped with a six-speed manual transmission don't perform as well.

But while an electric Bronco may arrive in the future, Jeep already has a plug-in version of the Wrangler.

The Wrangler 4xe is a plug-in hybrid version of the SUV.

The Wrangler 4xe is a plug-in hybrid version of the SUV. (Jeep)

The 375 hp four-door Wrangler 4xe is a plug-in hybrid model that can travel 21 miles purely on electricity before its four-cylinder gasoline engine kicks in to provide extended-range driving. The 4xe’s combined fuel economy rating is listed at 49 mpg, but that assumes a typical driver who starts every day with a full charge. In extended-range mode, the combined rating is just 20 mpg.

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On the other end of the spectrum, you’ll find the new 475 hp V8-powered Wrangler Rubicon 392, which guzzles gas at a combined rating of 14 mpg.