Truck shopping

My brother says his 2.7 gets good mpg. The salesman himself told me the 3.5 doesn't do what it's supposed to. I have two friends with Tundras. They both love them, except for gas mileage. 15 isn't too good compared to the big 3.
I just drove a 2018 Expedition with the 2.7 as a rental for 1500 miles...Decent performance in the northern Rockies. Mileage was just pretty much as expected for what the vehicle is... averaged something like 18.5 mpg in mixed interstate and rural highway driving. Got the same in a Nissan Armada with their V8 in the same territory a year before. The one thing I noticed....it had a 10 speed auto trannie. Goodness!

I really would not want that highly stressed engine, doing 1.5-1.6 HP per ci and the turbo's for anything I was keeping for years and years, and not for towing or hauling.