Then yr Satria can go 12.1KM/L which is not very good, my friend. City or highway? A lot of bumper to bumper or just smooth ride? My Saga Aeroback 1.5 Automatic manage to get 12.7KM/L on 60% highway and the rest is smooth city ride.
I use KM/L coz it wont get affected by fuel price and still applicable when someone else read this in few years time. So to say my 50 ringgit can go how many KM is not very accurate. To get a more accurate measurement, use the station pump. Better to use back the same pump each time and pump full, then reset yr meter and begin yr journey. Next round go back to the same pump and fill the tank full again, note down the litres filled and also the mileage traveled. Say u need to pump 40 litres to get it full again and yr car meter shows 450KM then u press yr calculator 450 devide by 40 = 11.25KM/L.
Knowing yr tank capacity also good coz say yr car red light comes due to low fuel and u start to panic and start looking for petrol station and it happens that area wont have a station in another 50KM and u may think that you are in deep shit but what if you are able to tell how much fuel is left and how much further you could travel? That is possible when you know yr tank capacity and yr car's FC which is around 11.25km/L (for the example above). Ok, here is how, say yr tank capacity is 45L, go pump full and travel till the low fuel light comes on and directly go fill up full again. If say u need to fill 35L to get it full, meaning fuel left during low fuel light comes on is 10L left. Now do the maths, 10L multiply 11.25 for each litre you get approximately 110KM. To squeeze the figure further, off the aircond and be soft with the pedal and relex, cheers :)