best for out of city drives

Hello,
I take my innova to a rural hospital three times in a month. The first half of the journey is on the calcutta- bombay section of the golden qudrilateral which arguably is among the best roads in India now and the last half is through proper rural roads. Approx round trip is 500 kms.I drive one way and my driver drives the other and I might add that I just take my driver along because I need to sleep on the way back otherwise I may miss my next mornings work.
This is by far the most exciting vehicle to drive, very steady at high speeds and handles very well indeed. Takes the smooth road and the pot holed roads equally well though the last row is very uncomfortable on the rural roads, but I may add that this will be the case an all other vehicles.
Milage is very good for a vehicle of that size, though the engine while standing is noisy but the vibrations and the noise disappear  when you cross 50kmph.
There should have been a sixth gear because the accelation in the fifth feels very much like the fourth and I am sure that will not be good for the milage.Issue with the differential Iguess.
I am a six foot fat doctor and the drivers seat and position is very comfortable as are the rear seats and I really enjoy driving the car. Good AC good music, good everything.
I just love it.