the Nissan Pathfinder can tow 5000 lbs and the Murano 2016 only 1500 lbs, how is it possible if they both are almost the same size, engine?. am I missing something?.
Good question. While they both employ the same engine, there is a list of several other variables that come into play here. Different vehicles are constructed with different ideas in mind when in comes to towing capacity. The axles of the vehicle, the braking system, the steering system, and the suspension of the vehicle along with their various associated controls are all integrated into the maximum towing capacity that any specific vehicle can attain.
That being said, the Murano is designed to act more as a crossover vehicle (vehicle built on a car platform while combining various SUV features) while the Pathfinder is meant to relate more closely to an actual SUV (sport utility vehicle). There are whole articles online describing the differences between the two vehicle types. Like this one http://www.autotrader.com/car-shopping/suv-vs-crossover-whats-the-difference-215843
To sum everything up, the Murano is meant to be a smooth riding, passenger comfort-oriented vehicle while the Pathfinder is designed for rougher use. The essential drive-train and suspension components of the Pathfinder make it a much more robust towing-oriented vehicle than the Murano.