does this trucks have different engine configuration? I'm kinda wondering why is this an issue?

Bless that car for having that kind of tune setup despite having a bulky body. The 20hp is a significant power increase to the car. This is a better aid rather than having the car mechanically tuned by replacing some engine components to jump up the power.

what would be the benefits of this kind of setup? Does gonna consume less fuel without compromising its power while running on 4 cylinders?

is it hard to tune the vehicle? I would love to make my truck run faster but consumes lesser fuel does changing the dimensions of the tyre would make it more fuel efficient?