Car Fuel Consumption Calculation

Didn't we go over the 5% error factor last week...?

We should probably just stick with straight math and push the "I believe" button...

the most important factors are, engine efficiency, weight and aerodymanics. how to calculate the fuel milage involves many engineers with different talents and many practical tests that costs millions of dollars.

Fuel consumption is how much fuel is used in an amount of time(Like say 3 gallons per hour)... MPG is how many miles you get per gallon....Most cars will tell you how many MPG you're getting nowadays....how much further you can drive with what fuel is left...your average speed, and more... If you insist on doing an independent calculation, then the method mentioned above is how it's done, and should be done several times to get an accurate average....It's hard to say how much driving time is spent stopped for whatever reason, and how much time is spent at what speed, how much acceleration is used varies from person to person, so their fuel mileage would be different, depending on whose driving....So your answer will be for the person being tested, in that particular car, under those certain conditions, at that time of year, using that particular fuel type, and , of course, will vary....

One could also look it up in the manufacturer's published test figures, which appear as part of the sales information...

I like your #1 response.

That's the only way to arrive at the fuel consumption of your particular vehicle, with you at the wheel.

Response #2 makes no sense at all.

It depends on how accurate you want to be. Post #1 will give you a pretty good idea, however refilling your tank is not an exact method. For instance, each pump will have an automatic stop point at a different level. Also, how hot or cold the fuel is will also have an effect. Also, your odometer may not be calibrated properly or other factors like low tire pressure, over/under sized tires, etc will give you a false mileage reading.

If you want to get an accurate fuel economy, you'll need to buy a meter to measure the fuel being used. You install it in your fuel line and the meter measures the amount of fuel which passes through the meter. Next, you measure the miles driven (I recommend using a GPS unit, which will be more accurate than your odometer) and divide by the fuel used.