Recently went to CII maintenance expo and came across information from Petroleum Conservation Research Association for improving the fuel efficiency of our four wheelers.. I found the it really informative and it has actually clarified lot of confusions. Few of the important points discussed were :
1. Stop the vehicles if the wait time is more than 15 seconds ( Based on research done for Delhi Roads ). I used to think that its 1 minute ..
2. Most of the cars are most economical if they are run at 45 kmph , Very tough to ride at such low speeds though!
3. Try to run the vehicle in top gears. It should be correct gear too !
4. Use of clutch only for changing gears.
5. Cleaning Air Filter, Fine tuning of engine.