Our 2001 Sequoia Limited's computer claims to get about 20 mpg even going 70-75, and claims as high as 22 going bout 65, even 25mpg drafting behind a big truck, and in its 70,000 miles claims to have averaged 17.5, though quite a bit of highway. Though on constant 4 hour trips the car somehow manages about 400 miles on the tank... a realistic 16 mpg

. On the last run of gas i've been doing constant city driving with literally no speeds above 40 on pretty average throttle and am gonna get about 12 mpg on this run, sometimes full of 8 people and cargo though
Overall I think the Sequoia gets decent gas mileage for an SUV of this type. On the highway it is similar to my very small 1995 Pathfinder I had a couple years ago, loved that car though, till the thing rusted out, thanks to New York winters.
But indeed, mpg shouldn't really be that much of a concern in any big truck or SUV, unless Ford's supposed hydraulic hybrid system that gets prius like gas mileage in the F150 actually works.
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1988 Nissan 300ZX 5spd 60,000 Miles
1995 Nissan Pathfinder (sold, rustbucket)
2001 Toyota Sequoia Limited