How to run your car more with less fuel and make it fuel efficient?t?

Most of the people don,t know that there is a way through which your car cover more miles than normal.
For this i won,t say you that you buy my product or anything its just a simple method that running your engine at low rpm(revolution per minute), That means change your gear little bit early say 5000 if you change your gear at 6000 or 7000 rpm but not so early that your car loose power.
Similarly when you are going on a constant speed then choose the gear where your car engine is in 5000 rpm range.
For people who don,t have rpm meter installed in their car they simply predict from the sound of engine.
this method can save up to 10 to 15 percent of your fuel , But only disadvantage is that you have to sacrifice the acceleration.
Another advantage of this way of driving is low heat generation by engine. If you are going on a long trip in hot weather then its best method to make your engine cool.