Why am I not getting my suggested mpg's?

[JohnnyG]

I know this topic is closed, more than likely because it has nothing to do with "car and truck gas engine oil", but I think, given the amount of confusion and misdirected faults, the administrators might consider a section on fuels.
At any rate, I would like to say this regarding the original post. Your suggested mileage has NOTHING to do with what you might get in the real world. It is not intended to even approximate what mileage you might get in the real world and any similarities to actual milage are purely coincidental! The reason for this is that the posted milage numbers are calculated BACKWARDS from the amount of emissions measured at the tailpipe. Less emissions = higher mileage numbers! This is a farce perpetrated on the American public MANY years ago by the EPA which has become the standard for all companies wishing to sell cars in the U.S. It just so happens that most times a higher number on the window sticker gets close to a higher number in real life, and can be used as a general guide when deciding your purchase...but by no means is it now or has it ever been meant to portray the ACTUAL mpg that you might expect to get from that car, EVER.

 

[TomJones76]

Johnny, can you offer a citation for this assertion. I'm sure you're telling the truth, but I'd love to see the way the government words this.

 

[JohnnyG]

It's been a long time ago, when they first started putting mileage numbers on the window stickers. (late 70's or early 80's?) I'm sure the actual wording is now buried under a mass of amendments and additions, but it never went away. The numbers on the window stickers are purely theoretical as I said before. There is a standard dino run, every vehicle goes through it for EPA certification, the tailpipe emissions measured and the fuel mileage calculated backwards from the results. Maybe an internet search will turn up some facts, I've lived with it so long I just accept the numbers for what they are worth...almost nothing.

 

[XS650]

quote:

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Originally posted by TomJones76:
Johnny, can you offer a citation for this assertion. I'm sure you're telling the truth, but I'd love to see the way the government words this.

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This indicates that Johnny had it right, but after reading the last part of it, I'm not sure what it realy sez.

Amazing but true:

"Do NHTSA’s CAFE values differ from EPA’s fuel economy data?
Three different sets of fuel economy values- NHTSA’s CAFE values, EPA’s unadjusted dynamometer values, and EPA’s adjusted on-road values exist. NHTSA’s CAFE values are used to determine manufacturers’ compliance with the applicable average fuel economy standards and to develop its annual report, the Automotive Fuel Economy Program Annual Update. The EPA’s unadjusted dynamometer values are calculated from the emissions generated during the testing using a carbon balance equation. EPA knows the amount of carbon in the fuel, so by measuring the carbon compounds expelled in the exhaust they can calculate the fuel economy. EPA’s adjusted on-road values are those values listed in the Fuel Economy Guide and on new vehicle labels, adjusted to account for the in-use shortfall of EPA dynamometer test values. "

That was quoted from:
http://www.nhtsa.dot.gov/cars/rules/cafe/overview.htm

All that said, I find the sticker highway mileage numbers to pretty darn reasonable for cruising at a steady 65. Sometimes I beat them, sometimes not.

 

[Patman]

The original topic wasn't closed, simply moved to the mechanical section, so continue the discussion in there please.