its indeed a very nice thread, I am still reading it, half way through yet. I tried some of the tips on my trip to Peshawar from Lahore. In last leg, from Islamabad to Lahore, I got ~20km/l in the following conditions:
- car: 2002 vitz
- load: 6 adults and a baby plus some load in the boot
- speed: cruised mostly from 100 - 115 km/h
but i tried not to give a lot of gas, i just accelerated gently and tried to maintain a stable speed without opening the throttle a lot and try to use slip streams at a safe distance
one thing that probably has a role in getting good mileage is engine oil. using good synthetic oils of low viscosity should also help in improving mileage. and the long drain intervals of synthetic oils balance off their extra cost and you get better engine life as a bonus