it's 4wd drive, google suggests a navara(?) has 7 speeds, isn't 50-55mph in 6th more efficient - given their target use, optimising the gearing for dual/motorway speeds sounds odd ?
This gets very complicated - the Navara is not full-time 4WD it is rear-wheel drive for road use. There are (in the UK) essentially two variants of the D40 - the 2.5L V6 which is designed as a workhorse and the 3.0L V6 (V9X) like mine which were designed as "lifestyle" vehicles (with fancy seats and a Bose premium sound system, etc. heh - so not your typical builders truck).
The 2.5L behaves like you are saying, the V9X is a "luxury SUV" engine and uses transmission and electronics based off (but not the same as) what is in the 370Z - it uses silly software tricks and different gear profiles low vs high to try and combine the best of both worlds and while it mostly works isn't flawless - for instance if I get stuck behind a cyclist power delivery becomes very bursty as it can't quite determine what I'm trying to do.
Then it gets all different again for the older and newer models than the D40.