Question Help With Math - Calculate Km/l - Car Consumption

[douglasrac]

Hi,

I'm making an Access database to help me register my fuel consumption, but I'm having problems to built the function.

I have the following data, that I will register every time I go to the fuel station:


Liters I'm putting in the tank
Current Km
Amount of Km I could run considering the amount of liters inside the tank

With that I think its possible to calculate the average km/l, Im just having a hard time figuring out.

Example:

Liters: 15
Actual Km: 0
Possible Km: 30

Meaning I just took the car out of the dealer ship and put 15 liters of fuel, but the computer of the car says I could run 30 Km with the actual amount of fuel in the tank. I cannot know how many liters.

Then next time I go to the station I register:

Liters: 15
Actual Km: 200
Possible Km: 20

So you can see I run 170 Km (200 - 30). Now somehow I have to discount the current liters inside the tank (possible to run 20 Km with it). Maybe using the latest km/l as base?

 

[Pat Hartman]

You have to pick a point to start "counting" and since you can't start with an empty tank, you start with a full tank. So today the odometer reads 100 and the tank is full. Next Friday, the odometer reads 700 and you put in 15 liters so for that tank you averaged 46 k per liter. Next week the odometer reads 1600 and you put in 14.5 liters so the average for that week is 62 k per liter and the average for the two weeks is 1500/29.5 or 50.8. So each week you can compute the average for that week and the running average.