I'm really surprised they haven't made a small displacement V8 ecoboost honestly. If they put as much engineering effort into naturally aspirated V8s as they have ecoboosts, I feel like they'd be nearly just as efficient if not more. Hell, Car and Driver just tested the new GMC 4cyl truck and it get's worse gas mileage than it's V8 cousin. Just goes to show it's not all about cylinder count (which most of us knew anyway).
I hate to admit, but I'm afraid the Gen3 will be an ecoboost hybrid. I'm still holding my breath for that new Super Duty engine though. Or, just imagine the TRX hits with 700hp hellcat engine. What are the chances Ford would just drop the 700+hp Mustang engine in the Rap? Very slim, but I feel like it's a small possibility because manufactures play the numbers game all the time to try to best each other.
"I'm buying a Raptor for mpg" said no one ever. I wish Ford would realize that.
A lot of people on this forum don't understand how turbos work and what makes it efficient.
At full boost, it is doubling the amount of air entering the combustion chamber. That also means it is doubling the fuel being consumed. That gives our 3.5L V6TT the appetite of a 7.0L V12! There is no free lunch and to put out 450 hp takes 450 hp worth of fuel regardless of how many cylinders there are.
The fuel economy benefits come when you are out of the boost. That's when we are only feeding a modest 3.5L V6 instead of a far larger V8. It is the ultimate form of "cylinder deactivation".
The C&D article you referenced stated they were in the boost when driving their fuel economy run at 75mph and is why it consumed as much fuel as the larger engine. They even admitted as much in their article. The big difference in MPG comes when out of the boost at speeds around 55mph for Chevy's I4TT.
As for strapping on an electric motor to our 450hp V6TT that would give us an obscene amount of torque off the line, I say bring it on!