How does RPM of a car affect the mileage

Hi - I own Santro Xing and this car doesn't show RPM while driving. Can someone explain what RPM is and how does RPM impact the mileage and what are the general rules?

RPM-stands for Revolutions Per Minute or the speed of the engine. The faster it revolves the faster and more numerous the combustion cycles and hence the fuel burnt.

Without an RPM gauge it would be hard to judge the exact RPM's. Drive the car at the appropriate gear for the at hand load for the best FE from the engine.

To add... change to 2nd at 10-15, 3rd at 20-25, 4th at 35-40 & 5th at 50-55. This will help keep the rpms at optimum/advantageous levels, and derive good mileage (Santro generally returns mileage of 11-13 in city & 15-17 on highway - depending upon driving conditions & style).

to be more precise, keep a hysterisis......

While Accelerating

 shift to 2nd after reaching 20kmph .....  shift to 3rd after reaching 30kmph .....  shift to 4th after reaching 40kmph .....  shift to 5th after reaching 50kmph .....

while deaccelerating

5th to 4th after going below 40..........

4th to 3rd after going below 30.......

3rd to 2nd after going below 20.....

2nd to 1st after getiing stopped to standstill.

cheers

Avoid the '.......'  MODS

Kindly explain what you mean by the above-thanks

Thank you everyone for your valuable inputs. For cars that have a meter to show RPM, what rules should one use? I am planning to buy Linea Dynamic and i think it does show RPM.

I have often taken objections to this "drive in this gear at this speed" concept. Here is the basic thump rule for your engine and for your mileage:

1. When you want to accelerate, slot in a lower gear that pulls easier rather than lugging in a higher gear, where you would press the throttle very hard. This lower gear will generally be different based on the load, slope, etc. As a thump rule, never try to floor the accelerator in a higher gear just because vehicle is not accelerating enough. Just lower the gear, accelerate and shift up when you think you are already in the speed you want.
2. When you don't want to accelerate, i.e. to remain the same speed, slot in a higher gear that would make the car happiest to roll without too much retardation. This will also be the gear, in which you can just tap on the throttle only once in a while to maintain that speed. This again obviously is not in a gear that the engine would be lugging (giving jerky stalling feedback).

You neither need an rpm meter for this nor to maintain a rigid speed vs gear combination. RPM meter would help in initial days when you don't get the feel of the engine.

 Sharing a few links from Hyundai and Fiat (the technique match with what I see in my instantaneous fuel consumption indicator on my Linea)

http://hyundai.co.in/fuel-tip1.asp?pagename=fuel

http://www.fiat-india.com/fiat-connect.aspx

by hystersis, i mean, diffrent rules for accelerating and deaccelerating......

like we shift up to 3rd gear after 30kmph while accelerating but keep the 3rd gear till 20kmph while deaccelerating....... same for all other gears..... so we are not following the same rules for acceleration and deacceleration but keeps an hystersis.....

Thanks

Avoid the '.......'  Consider this a final warning-MODS

Opendro, for new or not-so-experienced drivers it's easier to follow the gear-speed ratio.  The ones mentioned are good enough (in my opinion) & would by & large take care of the aspects discussed by you.  Besides, soon the drivers would realise the changes they need to make - depending upon their driving conditions & requirements.

@Amit-never heard about the word 'hystersis' hence asked. 

A similar sounding/looking word means very different-'hysteresis'