With turbo cars, the thing is that if you take performance from the engine it gives 7-8 and if you drive calmly, like an SUV should be driven in city then you can achieve around 10 depending on traffic. I have a 1kd myself and people claim it gives 9 km/l but i usually get around 11 with a few acceleration pulls and moderate traffic.
Considering your gli is only giving you 7.5, i would assume that you have a heavy foot and with a heavy foot prado will give you the same mileage. i.e. 7.5. If you tailgate other vehicles and apply too much breaking then you are gonna get worse mileage. With an SUV i had to change my driving habits a lot.
That being said Prado is not comparable with a Gli in any way. All the dynamics are different. Also SUV in daily driven capacity is not as agile as a car. There are compromises on both sides.