When you mention your gas mileage, how do you figure that out? How can you be so accurate? Even if you try to use the gas light as an interval( the miles accumulated till the gas light comes on) you still wouldn't know exactlly how many gallons of gas you've burned. Unless you drive it till the last drop then you divide that by the capacity of your tank ( 13.6) you can't be that accurate.

Filling up the car when the light comes on then sustract that amount from the total capacity(13.6) doest not help either. Simply because the amount flactuates considerably, even though I fill up immediately within mile or two
after the gas light comes on. How much does it flactuate? Up to two 2 gallons sometimes!

On a recent trip I noticed that it takes around 9 gallons to fill up my tank in other states vis a vis 11 & up in CA !!! how accurae are those damn pumps!

 

pumps should be fairly accurate as they are tested at random by the state.

How you do it, is fill up you tank, hit the trip meter.

Run until you fill up again, at that point fill up at the exact same pump you filled up before to prevent variation in pumps.

Take how many miles you drove on the trip meter, and divide it by how many gallons of gas your tank took to fill back up. Simple as that

 

I should get close reading every time I fill up. It never happened. As I explained it flactutes tremmendesly. I would have a different reading for the same miles driven! The key here is how much doest it flactuate? If it's a slight variation then you can calculate the margin of error and get an acceptable reading. In my case, it 's huge; up to 2.5 gallon!

 

Yup that's the best way. Make sure you buy gas at the same pump if you can. Cause a slight incline could fill up more or less in your tank.

But yes MPG will fluctuate from week to week depending on how you drive, how often you turn on/off your car, how long you sit in traffic, etc.

 

yep, fuel economy changes a lot depending on how and where you're driving. I've gotten 41 mpg cruising across nebraska, and 22mpg doing mountain runs or pizza delivery--all in the same car.

 

You guys missed my point! The gas consumption depends on how you drive. No question about that.

It's about filling up when the gas light comes on, which it should give you the same amount, well relatively. I'm pretty sure that the gas light is accurate. I'm assuming there is some sensors (or something) in the tank that would initiate when the gas level hit a certain point. I'm also assuming that it should comes on when there's about 2 gallons in the tank. The system should be pretty good cause the guys at Honda doesn't want you to get stranded within few miles after the light comes on. So it's safe to assume that the gas light is pretty accurate. So, let's say the gas light comes on with around 2 gallons left in the tank, and given the capacity of the tank(13.6) you should fill up the tank with around 11 gallons and that figure has to be very close each time you hit the pump. So how do you explain the flactuation I'm getting at the pump? up to 3 gallons?!!

The only explaination is ....it's that automatic shut off when you fill up your tank. I think that the tank takes in a different amount each time you fill it up and that's how I end up with a different amount when I fill up. You can argue that, that automatic shut off should be accurate too; gas expands when exposed to heat and might cause some damage if it's overfilled. Let me close on a funny thing happened to me; I filled up with 14.3 gallon !!!! (capacity 13.6) !!!!

 

First one could be if you've used a different pump, you're sitting on an incline or flat.

Second one sounds like the pump needs to be re-calibrated. If there is such a thing.

 

There is no accuracy expressed or implied in a fuel gauge, or the idiot light. The idiot light is only there so that you take notice when it starts to get low.

Park on an uphill and watch the gauge. Park pointing downhill and watch the gauge. Keep in mind, you still have the same amount of gas in your tank. What happened to your gauge?

The added capacity beyond your tank = the fuel filler neck. The capacity specified in your owners manual is for the tank itself, not the fuel lines and filler neck.

bambrose told you how to calculate your MPG correctly. That's what you should pay attention to.

 

There is such a thing, and it's regulated by the Federal Government. If gas stations don't have their pumps checked and properly calibrated, they won't legally be allowed to sell gas in the US.

 

I do it how bambrose said. Make sure you are filling up full tanks of gas. It keeps it more accurate than if you were to fill up a half tank at a time.