Measuring Fuel Economy and Tank Size

[sjrobinson]

So I looked up the specs of my car online. It says it has a 17 gallon tank but It does’t seem like it. The way the needle moves compared to my fuel economy it doesn’t add up. I don’t think I have a fuel leak but especially for my car it seems like itd have a 12 gallon tank. And no its not my driving either. Anyone know why? Is it possible that the tank can never be filled as high as it says or maybe the gauge is off?

Topic

[johnzcarz]

Some cars have a weird shaped tank and it causes the fuel gauge to do funny things. For instance, if i fill up one of my cars it will do 100 miles before the gauge ever moves down past ‘Full’. Then in like 25 miles it moves to the 3/4 mark. And almost every car I have owned starts warning me I’m low on fuel when i have several gallons left in the tank…..even after i drove it way past my comfortable zone for driving with the fuel light on, I still have 2-3 gallons left…I guess it’s better than the fuel warning light coming on and the engine sputtering to a halt at the same time.

If you want to check your fuel economy, regardless of tank size, here’s how you do it:

1. Fill up.
2. Reset your odometer.
2. Drive as long as you can on this tank of gas.
3. Fill up again – BE CONSISTENT! If you stopped fueling in step 1 when the pump clicked, do it the same way here.
4. Write down how many gallons of fuel you pumped, and the odometer reading.

Now just divide the odometer reading by the gallons used – and that will be your fuel mileage.

If you are getting the MPG you expect, and you are sure the tank size you looked up is correct, then it’s just the way the gauge reads.

[twiggy]

+1 on above post it’s what I do.

[Matt]

Here’s what I do to test fuel economy on my vehicles. Run the vehicle til the fuel gage hits a set point, say 1/4 tank. Then pump exactly 10 gallons into the tank. Then, reset yer trip odometer, or write down your vehicle mileage. Then, run the vehicle until it hits the point you set, like the 1/4 tank on the gage. Then, divide how many miles you have driven by 10. Bam, you have your average fuel economy. Similar to johnz method, but less math, and I LOVE less math 🙂

[Author]

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