re: Ford will be introducing a diesel in the F150 later in the 2018 models

They run light loaded at low efficiency and burn more fuel and break more. People aren't actually working those engines because the people who really do work them buy 3/4 tons. Having that much torque also drives the cost of the vehicle way up since the rest of the drivetrain has to be built to handle it.

Put a modest 4 banger diesel that makes similar peak torque numbers to your small gas burner and you'll start having sales. Keep putting 550 ft-lb V8 shite in small trucks and you won't sell shite.