A Ford F-150 with camouflage material on its bed was recently spotted testing in Dearborn, Michigan, but the most interesting aspect of the truck was hiding in plain sight.

Clearly visible under the truck’s rocker panels is a Venturi-type exhaust tip, similar to the ones used in Ford’s Power Stroke–powered F-Series Super Duty pickups. That, combined with the engine noise our photographers reported, suggests that Ford may bring a light-duty diesel to its 1/2-ton pickup, the F-150.

Ford recently federalized a 3.2L I-5 diesel for the Transit van, where it makes 185 hp and 350 lb-ft, but by comparison, that doesn’t even out-twist the smaller 2.8L Duramax I-4 found in the GMC Canyon and Chevrolet Colorado. For a diesel Ford F-150 to be competitive, it would need to turn the wick up on the 3.2L Power Stroke.

An alternative solution (and the one currently favored by industry insiders) is repurposing another manufacturer’s diesel engine. The mill powering the F-150 seen here is rumored to be the 3.0L “Lion” V-6 currently in use in the Range Rover and Range Rover Sport Td6. In those applications, the engine produces 254 hp and 440 lb-ft, which surpasses both the Duramax 2.8L and the VM Motori–sourced 3.0L EcoDiesel V-6 found in the Ram 1500. By way of comparison, the Ram’s light-duty diesel produces 240 hp and 420 lb-ft. Ford could retune the Lion V-6 for more low-end grunt at the expense of overall power and still come out ahead.

Also helping the F-150’s diesel case is that its motor is likely tied up to a 10-speed automatic transmission, as on the F-150 Raptor. The gearbox, along with the F-150’s much-ballyhooed weight-loss regime, could give it fuel efficiency numbers that crest 32 mpg.For its part, Ford has not copped to an oil-burning F-150. The company is still very firm in its product strategy, which prioritizes weight loss and downsized, turbocharged gasoline engines. Additionally, rumors are flying that Ford is planning a hybrid F-150, so development dollars could get earmarked there, rather than toward diesel. Or maybe the company is selecting (D): All of the above.Until we get an official announcement from Ford, we’ll just content ourselves by dreaming about an oil-burning version of our 2015 Pickup Truck of the Year.