I would generally agree with this point of view. But, my F150 Ecoboost consistently gets 10 to 10.5 mpg pulling our 8,500 lb 5er at 62 mph. I think that is darn good. We are talking 3,000 mile trips here. No fluke or outlier result.

 

A lot of this comes down to physics. It takes a given amount of fuel and air to create a requested level of power. We often forget that diesel has ~14% more energy than gasoline per unit volume, hence the better MPG.

 

I think it will be nice to have a bigger CI naturally aspirated choice in the super duty. Actually working the truck will result in tolerable mpg vs a turbo gas engine. I have had the chevy 8.1 and the 3valve 6.8 v-10. Both i was happy with the torque and mpg towing and unloaded. Usually towing was 8-10 mpg, unloaded 12-14. I bet they can squeeze the same mpg out of this mythical 7.x liter engine they get from the 6.2 now.

I would be happy with 3 engine choices in super duty.
5.0 turbo gas (mild boost, not much)
6.7 diesel
7.3 gas n/a

 

I get to spend a little time with the 3.5 EB. Put the Ram in the shop for some service, so I have a 2017 Expedition EL for about a week, thanks to my friends at Enterprise - at the Ford Escape rate, no less (because that's the only SUV they had handy)! Haven't driven a gasoline turbo since my Dad's 1988 Thunderbird Turbo Coupe, so this will be interesting. Don't have reason to drive it like I stole it, but I'll see how it feels compared to an unboosted gasser or my usual diesel. I admit to being old school as far as truck engines... big I-6 or V8 gasser, or a turbo diesel. So I'll see if something half the size of this coming 7.x meets with my approval

 

The 6.7L can be configured in the F-650 at the 270/675 rating (base option) but also can be ordered at 300/700 or 330/725. Still a de-rating, and Ford has published a B10 engine life rating of 500k miles at the 330HP rating.

While you are correct on the V10 output for the 650/750 trucks, oddly enough the same V10 in an F-550 is rated at 288HP and 424lb-ft...a further de-rating from the much larger 650/750 trucks.

Allegedly the V10 continued because the 6.2L was unable to meet medium-duty engine demands. Initially, the 6.2L V8 was supposed to completely replace the V10.

In reality, even a more powerful 6.2L would seem a bit small for the 650/750 class.