ApostolicFire

From an old post I made (in addition to the instructions, don't top off the tank or go any extra 'clicks').

jamesgang

Slightly different level
The car parked in my driveway with 234,000 miles on it was set up in such a way that doing as you say above would net me a full 100 miles less per tank than topping it off. Was that tank full at the first click off? Thats 3+ gallons.

bB2NER

He wasn't talking about how many miles per tank He's talking consistency in order to get accurate MPG's
In my Econoline van I can squeeze another 8 gallons in it after the initial click. It all depends on tank design.

jamesgang

I get it. And relying on the 'quirky' shut off of various pump handles will, in no way, give us a reliable/consistent base to calculate mpg. That is, one time you can 7 gallons, the next 8, followed by 6.5

OneBadBox

Say the pump click off varies by 1 gallon. Over the course of 33.3 ten gallon fillups the most you could be off is only one gallon. You can't possibly be off the same direction every time, else your tank would already be full or require 20 gallons after only ten fillups. Now using 332 gallons and 10,000 miles we get 30.12 mpg and using 334 gallons we get 29.94 mpg, a span of less than one percent.

If you take this car and fill to the first click every time your tank will not vary by three gallons, none of the pumps will get anywhere near what you consider full. They will all be in a range of about 1 gallon, I bet less.

bB2NER

WHY is it so hard to understand that you don't need to fill it to the top to get accurate mileage figures. As long as you keep track of TOTAL miles and TOTAL gallons, that is all that's needed PERIOD. The CLICK on the gas pump is NOT part of the equation PERIOD.

emiller

If you drive a certian number of miles and you dont fill all the way then how do you plan on figuring out MPG? You will have no idea how much gas you actually used to drive that number of miles. Its just like filling it by adding clicks. If you do 5 clicks 1 time and none another then you didnt fill it to the same amount as you did last time and you will have no idea how much gas you actually used.

tacomatrd

Buffs? Read you BMW manual and it will tell you overfilling finds its way into the charcoal canister and casues problems with emissions and more! First click and thats it. O wait you dont drive beemers gosh my bad

jamesgang

If you take this car and fill to the first click every time your tank will not vary by three gallons, none of the pumps will get anywhere near what you consider full. They will all be in a range of about 1 gallon, I bet less.[/quote]

Here are my two points;
1. I want an "acurate" mpg reading when I do the calculation. It is as simple as that. The way I do it is as acurate as one can ask. Otherwise, I could just look at the original window sticker.
B. The reason I fill up - top off - is personal. Driving, on average 175 miles per day - living on a border state (higher taxes on one side than the other) - it makes economic sense to top off - it saves time, saves gas, and save dollars. SIMPLE AS THAT.

jamesgang

ptmccain

As the person who started this thread, I would like to say that I think we've run this topic well into the ground.

I think we can move on now.

oldmanatee

Why is it sooo improtant to figure mileage down to the foot????
No matter what the mileage is, when the gage reads E, you have to get more gas.
Just fill it up til the 1st click off, then squeeze in til the next dollar just to keep from having a lot of loose change in your pocket, because change is heavy and will affect your mileage. I also don't drive after a large meal.
If the mileage starts to drop considerably, have the service dept. check it out.
If you squeeze in extra GALLONS at each fill up, you will severly screw up your ODB II sensors. Not covered under warranty like others posted.

emiller

Here are my two points;
1. I want an "acurate" mpg reading when I do the calculation. It is as simple as that. The way I do it is as acurate as one can ask. Otherwise, I could just look at the original window sticker.
B. The reason I fill up - top off - is personal. Driving, on average 175 miles per day - living on a border state (higher taxes on one side than the other) - it makes economic sense to top off - it saves time, saves gas, and save dollars. SIMPLE AS THAT.[/quote]

Finally someone with an actual reason for topping off. I do the same thing because gas usually costs more near my job than near the apartment. Although I dont drive that far or across state lines. I always fill up in Ohio when Im there though for the cheap gas.

TheScionicMan

Accuracy in mpg vs. possible damage to the charcoal canister/ the environmental impact of spilled fuel/ poor performance due to emission system malfunction/ check engine light for evap system? I'll take a little inaccuracy, especially considering that the odometer has been proven to be inaccurate with stock tires and if you've changed things, then who knows?

I like the idea that we can compare how the xB responds to the pump, shutoff-wise. I don't know if comparing that to "the car in the driveway 234K on it" is as relevant...

jamesgang

When will one first notice "...damage to the charcoal canister/.../ poor performance due to emission system malfunction/ check engine light for evap system?..."?

I would think 19,000 miles would be time enough to start experiencing these symptoms?????
By the way, I'm not yet ready to ANNOUNCE my 41.264mpg without A/C and minimal highway miles. I'll hold off until repeated a few times. Its supposed to get hot again today - so likely the A/C will be in use.

I'm also doing a little informal test as to the gallons after 'click off'. I'll let you know how that goes.

As far as WHY the need to know the exact mileage to the foot. Maybe its the lesions I've been diagnosed with.

oldmanatee

So, what will happen when your mileage does vary?
I like to keep an eye on what I get, but if I get 10 miles less per tank, my world will still keep spinning. Likewise, if I get an extra 10 per tank, it doesn't mean Mom can get that operation.....
Yall must have every other problem in your life under control to be this worried over mileage.

As for when you should notice degraded performance due to cannister contamination, it will flash a code at a very low level because of gov't regs. All mfr's have to meet such strict pollution regs, there is very little wiggle room in the amount of vapors that are allowed a chance to escape into the atmosphere.
The best way to avoid a costly repair to something that has to last 150,000 miles is to not overfill the tank. Not only that, you don't risk the gas splashing out on you or dribbling down the paint job if you don't try to pack the gas in.

jamesgang

Uhm - maybe I should use more emoticons. I'm not taking it serious 'tall. In fact - I treat the gas mileage thing a bit like a hobby. Gives me a little som'en to do while driving. You see - I really CANNOT excede the speed limit in NY State. They've got my number.....So to speak!

Mom already had her operations. Thankfully my Dad was wise enough to buy additional insurance to cover such things.

When will this code flash? Based on what you know about my car - 19,000 miles with all but a couple/three tanks totally topped off! Will an idiot light come on to notify me of degraded performance. Or will I start getting poor gas mileage?
Where are these vapors escaping from again? And do they only escape from the 'topping off gas' but not the 'first click' gas?
I'd really like to see the car, and ALL its parts last 300,000 miles. One-Fifty will be like

oldmanatee

Thanks for letting me know that you were joking... I was worried that yall were really serious about this...

Now, for the codes and vapors, the cannister is designed to collect the expansion vapors from when the tank is full and due to external conditions, the vapors expand and due to the EPA regs have to go to a sealed container. IF, and it is a big if, over time, you have accidentally overfilled the tank the vapors and raw gas are vented into the cannister. The charcoal is designed to absorb the vapors, so after time, if raw gas has been vented as well, the cannister will be useless. I don't know how much contamination that requires, but the sensors then throw the code and next time the car is in the shop, the dealer has to by law, make the emission system legal again. In AL, that means he can refuse to release your car until you fix it. I am not sure, but if the code is serious enough, it could put the car in "limp Home" mode... talk about degraded performance!!!
And the ODBII regs are so tight.....It is a fact that ULEV engines are capable of exhausting cleaner air than it takes in.
All I was saying was why take the chance? Gas 'er up, stop at the next dollar, and hit the road...

VdubbsXB

With today's prices, the next dollar is only a couple ounces away. LOL

oldmanatee

Aint that the truth... I topped off this morning (one click only), from a half a tank, took $15!