How much fuel is your car using right now? None! it's parked in the garage while you read this at home. Or maybe you're reading this online while in the car, so how do you tell? you need some sort of fuel gauge, some sort of consumption meter or something right?
There are a couple of things that will affect the amount of fuel consumed by your car. How many cylinders it has, the type of fuel you use, the type of disctances and speeds you drive, and many other factors.
Well, it turns out that you do have a basic meter by which you can measure your fuel consumption, it's your rev countert>