As both established and startup automakers rush to build electric pickups, many seem to have forgotten a fundamental principle of pickup design: Trucks were meant to work.

Ford has announced it is developing a plug-in hybrid F150, and Ford, GMC, Tesla, and startup automaker Rivian are all working on electric light--duty pickups. What none of them are talking about is heavy duty pickups that spend a lot of time on the road and can help contractors and companies save thousands of dollars in fuel costs in their businesses.

For those customers, XL, a Boston-based conversion company, released a plug-in hybrid version of the Ford F-250 at the NTEA Work Truck Show last week. 

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XL beat Ford to the punch last summer, potentially by two years, with the release of the plug-in hybrid F-150, and it just announced it will taking orders for the Super Duty F-250 plug-in hybrid later this year. Puget Sound Energy has already ordered 110 XL vehicles.

The F-250 uses a 15-kilowatt-hour battery pack, but is not designed to have any all-electric range. Instead, the electric motor is designed to take the load off of Ford's standard 6.2-liter gas V-8 to boost fuel economy by a claimed 50 percent. The improvement should also reduce carbon-dioxide emissions by a third.

Since Ford isn't required to provide fuel economy ratings for heavy-duty pickups, it's unclear what that mileage might be.

READ MORE: XL trucks' Ford F-250 Hybrid gets California approval

The battery can charge on either a 240-volt Level 2 charger in a few hours, or a standard 110-volt wall outlet (Level 1) overnight.

The hybrid system adds 750 pounds to the weight of the truck, which reduces its payload by an equivalent amount. 

The truck has been approved for sale in all 50 states.

Customers can buy the truck from a Ford dealer in almost any configuration they like and have it sent to XL to "upfit" with its hybrid system. As a certified Ford eQVM upfitter, all of Ford's original warranties continue with the truck.

NOTE: This story has been edited to reflect the company's name change from XL Hybrids to XL.