For better highway mileage and enjoying northern areas try to find a decent well maintained Surf with 1KZ-TE.
I am used to get 7.75-8 km/l in city with full time AC on and its my daily runner.
I came back from Multan yesterday, I kept my speed around 80-90 km/h from Lahore to Multan and back on GT road and believe me it returned 10.85 km/l al hamd o lillah, tyre pressure was 30 psi all around.
And guess what I have reached the destination within the same time when i drive around 100-110 km/h because this time I have avoided excessive braking using some hypermiling techniques.
I believe in preventive maintenance and I have changed all oils (gear, transfer box, front rear diff) all filters regularly (air filter every 3rd oil change and fuel filter every 4th oil change) replaced front shocks, suspension bushes, gear mounting, new maxxis AT tyres, replaced first time its timing belt and bearing etc.
Mine has done 141000 kms original but in order to find this beast I spent almost an year but result is superb al hamd o lillah.