How to Count Your Car Fuel Consumption

How you count your car fuel consumption? Is it the right way? I join several forum, read several magazine, and have a chat with several people. And every time when we chat, when we are talking about car fuel consumption. There will always some people talk "Oh, I fill my car fuel two times a week", then the other people says, "Ah, mine has better fuel consumption. I have my car fuel refill one time a week."....
Stop!! How we know that his car really get better fuel consumption? There are a lot of condition may different from two of them. who knows how many mile they are taking for a week. Also, who knows how many liter of fuel they fill to the car when they go to pump station.
But still there are people use this method to compare their car fuel consumption everytime. We should know the correct procedure for counting our car fuel consumption. The way is easy. Full your car with fuel, make sure you can see the fuel with your eyes so that you can mark it on your mind. then reset the trip meter to 0. Now, have your trip.. enjoy.. until the time you need to fill your car again. lets say you go for 298km. Go to pump station to have your car filled. make it full and exactly the same level with the previous time you fill your car, you can remember the mark, isn't it? lets say you fill for 28.6liter. Now get the KM divide with liter. So, 298km/28.6ltr= 10.419. It means your car consumpt 1 liter when it goes for 10.419km. Got it? People usually state it 1:10.419 or 1:10.5. Simple isn't it? Now you can use this method rather than other methods.
Some car equip with MID that able to count the fuel consumption for you. In my experience, it can get different result when MID count the fuel consumption with the method I stated. The tolerance is 5-10%. So if you count your car have 1:10.5. The MID may show 1:10, 1:9.5, or 1:11.5. This different because sometimes air is trapped inside the fuel tank and we don't know how much air inside. This make the method has somehow tolerance for 5-10%. The MID also can make mistake in counting fuel consumption. there are 2 ways for MID to count the fuel consumption. First is they put sensor inside the fuel tank and the second way is they put sensor at the pipe that go to combustion chamber. sensor at the pipe is more accurate as it count the fuel goes out. Different with sensor at fuel tank, it count the fuel consumption by detect the level of fuel inside the fuel tank. this could be inaccurate as when the car move, the fuel will shake.
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