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:confused:

filled up today, and even though my display read 60.5MPG, i ended up with 53!! yikes, i don't think i've been that low all summer. i am not sure what's going on, but something seems to be a little "off" in the car.......i am getting an alignment and oil change tomorrow, but wonder if there's something else that should be looked at. i am at about 25,000 miles overall, the car's birthday is this month......

That would be typical for my car. I'm always off by about 10% optomistic.

That happened to me earlier in the summer. I had something good on the ScanGauge and something much worse at the pump. I'm pretty sure that it was either an over-read on the pump or else it shut off later than usual. It doesn't take much.

I need to compare manual vs FCD more, but with one exception, manual is better than FCD.

Here's the deal: and I'm sorry

Exact MPG is nearly impossible and inconsistent.

Depending on temperature, the molecular structure of the fuel mix expands at higher temperatures, resulting in what is shown as more fuel being pumped; and consequently, you are charged more per gallon -- however, due to the heat, the expansion of the fuel in the tank will allow less fuel to be filled in the tank. Regulatory agencies allow a certain percentage of variance based on temperature. The vehicle's or ScanGauge's FE gauge will be more accurate because it shows more of what fuel is injected (and how accurate your speed sensor is due to variance in tire wear and diameter of the worn tire). The pump method is perhaps the least accurate way to measure FE.

RH77

Hi Laurie:

___You have been commuting with a few days of 50 and 60 degree temps lately, right? Not much you can do about it unfortunately but this is where the hit starts :(

___RH77, because most stations tanks are underground, the temp of the fuel as it enters your tank from just about anywhere is relatively close. Feel the neck of the nozzle while you are filling and it is usually a lot colder then ambient in the summer in the deep south as well as the upper reaches of the Northern States. In the winter, it is above ambient but I will have to do some research as to what the average swings in underground tank temps are?

___Good Luck

___Wayne

My display is always about 2 mpg low. It's reading 55.3 now which means approximately 57.3

Hi Laurie:

___You have been commuting with a few days of 50 and 60 degree temps lately, right? Not much you can do about it unfortunately but this is where the hit starts :(



___Good Luck

___Wayne

good point, wayne. it's actually been in the 40s some mornings when i leave. i almost have to stop wearing sandals LOL.....

it's just strange that it read so much higher on the display, usually i am within 3MPG when i figure it manually.

did i mention i hate winter?

...did i mention i hate winter?

Come to Texas and you will hate summer in August.