W. Salam,
If you want better fuel economy, this vehicle is not for it. The gear ratio is not made for efficiency, but for torque and low and high 4x4 function.
If you still want it and can afford its fuel average, then go for a recent model, 2005+ auto or manual. There are some Nissan Kix 2012 model I've seen, they are basically same Pajero Mini, Nissan took it from Mitsubishi in 2012. Avoid modified ones, with engine and gear swaps.
All the best.