Automobile / Gasoline usage discrepancies

I've been noticing some very peculiar things going on with my car lately, some of which just cannot rationally be explained - and I have a theory.

Let me begin by stating what is happening, and what many individuals may tend to just ignore or take for granted. Gasoline mileage. We all know what's posted in the owner's manual and specs, Hummers are gas guzzling beasts while 'green cars' are far more efficient. Everything else is pretty much in between. But gasoline consumption still varies based on other outside factors like wind resistance or drag, air conditioning, partially deflated tires, varying temperature, road conditions, stop and go traffic, faulty/damaged interior car components, 'sludge' or buildup in fuel system, etc.

My car, a 2006 Ford Mustang V6 - has had wildly swinging consumption rates that just don't make sense other than some sort of tampering. I'm not talking about over the course of a single drive, I'm talking about months at a time. Let me explain. So on a full tank of the same grade of gas every time, the indicator denotes that I can get about 370-ish (give or take) total miles before empty. I drive the same daily route to work and the same way home, about 40 minutes each way. Every other time I drive I use a different vehicle.

Now sometimes I get the full 370-ish miles, but it fluctuates. For the past 5 months solid I get approximately 300 total miles on a tank. The gauge begins at 370 but it drops faster than this rate. Just before this period it was about 350-ish for half a year, and before that 310 for more than half a year. Before that it was pushing 400 for a while... I'm perplexed because it always falls in line with how the economy tends to be doing. I've tested all scenarios with windows down, up, A/C, everything to remove all outlying data. It's not seasonal, nothing has changed with the car, always get fuel at the same place and grade, not even the route changes. The fuel mileage literally gets better and worse, all factors accounted for, for no reason.

Conclusion: There is a computer chip in vehicles that manufacturers and 'big oil' own that can reduce your fuel efficiency whenever they want more money. This has only been tested extensively with my American made Ford, but others that know a thing or 2 about cars have noticed as well. Perhaps big oil companies also put something in the gas to make it less efficient as well? I believe after all of my experimenting that they have the ability to control this efficiency and do so whenever they see fit. Anyone in agreement or feel differently? I'll answer all questions about my 'controlled' experiments also if you think I am missing something or wasn't thorough enough.

I think the change in fuel milege has to do with seaons


Temp outside

Air flow into the car

Winds for resistence

these things vary month to month and would cause a damper on ur fuel

espically if there is increased activity in weather .


As for the computer fuel ratio, you would need some sort of system of communicating with the computer . Which could easily be detected if there was transmission of information going out your car into some system?

to much variables in your testing.
the only way to test this for real is in a controlled environment.

but who knows, you really might be onto something.

flagged so other can chime in

these last 3-4 months wouldn't have happened to be summer months now would they?

Same thing happens to my mazda, albeit probably not as drastically as it affects you and your mustang. Hot summer, hot road temps = very hot air on / near the surface of the road (which doesnt help a lower profiled mustang). the hotter air combusts quicker ie not giving each cylinder the optimal amount of power which in turn causes the engine to kick its revs up to compensate for the drop in power which guzzles more delicious petrol

i'm fairly positive that big oil doesnt control the mpg on your mustang.

in a warmer environment the tyres may stick a little more to the road surface than in colder climb and i've never seen a very accurate fuel guage yet which does include parking uphill or down hill and affect your initial tank readings so making the resultant mpg a bit off

When was the last time you got a tune up? Changed the injectors, changed the fuel filter, did fuel injection cleaner, new tires, tested tire pressure? Do you work a set shift, meaning are you on the road at the same time everyday or does it change? What is the average traffic like on your drive? Do you use your cell phone while driving, smoke, eat, drink anything?

Originally posted by fireysnowman29
these last 3-4 months wouldn't have happened to be summer months now would they?

Same thing happens to my mazda, albeit probably not as drastically as it affects you and your mustang. Hot summer, hot road temps = very hot air on / near the surface of the road (which doesnt help a lower profiled mustang). the hotter air combusts quicker ie not giving each cylinder the optimal amount of power which in turn causes the engine to kick its revs up to compensate for the drop in power which guzzles more delicious petrol

i'm fairly positive that big oil doesnt control the mpg on your mustang.

Hey, it was actually a little longer than the 3-4 months, but yes this time it does coincide with summer. However the past few years it's not always seasonal. Seriously! And the swings are INSANE, 370 to 300 total mileage is about 20%, and that went well beyond the summer hot months.

Originally posted by Vodo34861
When was the last time you got a tune up? Changed the injectors, changed the fuel filter, did fuel injection cleaner, new tires, tested tire pressure? Do you work a set shift, meaning are you on the road at the same time everyday or does it change? What is the average traffic like on your drive? Do you use your cell phone while driving, smoke, eat, drink anything?

Hey Vodo34861, in terms of tune-up I get this done every other year. Injectors, fuel filter not often. Fuel injector cleaner now and then at oil changes. New tires have not yet, tire pressure very routinely.

In terms of a set shift always a 9-5 approximately. Mostly highway miles, I need to fill up my tank once per week roughly, it's 38 miles each way about. Not much traffic except for 2 small parts (going against rush both ways). Don't eat, smoke, talk, or other distractions...except to sing along and 'rock out' on occassion...!

In terms of all the factors, a very important thing to note is it may be at 300 total miles for 7 months, then just spike to 400 randomly for 2 months without even a tuneup or cleaning. And this isn't just a faulty gauge, because the extra $$ spent or saved each week doesn't lie. Ive been driving the route for 7 years and know exactly when I tend to need to fill up.

Do you use different fuels....i mean like BP...ESSO...Texaco etc.

Supermarket fuel in the UK is pretty naff...its a bit cheaper but you dont get the millage from it.

Ive found that different companies make slightly different fuels, so one may get you 300 miles the other may get you 350 miles.

There are plenty of reasons as to why your cars millage has changed/dropped...i am almost certain its not because there is a chip in the car that changes the fuel consumption based on the economy.

Originally posted by Ajax
So on a full tank of the same grade of gas every time...

Just so you're aware, fuel manufacturers change the fuel compunds according to different seasons.
The "same" fuel, even from the same company, bought at the same gas station, is NOT the same all year round.

Just another thought, if you always buy fuel at the same spot, the calibration of the pump my be off, and you are not actually getting the same amount of gas. Among other things, is your check engine light on, or any other indicator? The computer controls in the car, have a safe mode if one of your sensors is not working properly. Just a couple of things to check.

Originally posted by loves a conspiricy
Do you use different fuels....i mean like BP...ESSO...Texaco etc.

Supermarket fuel in the UK is pretty naff...its a bit cheaper but you dont get the millage from it.

Ive found that different companies make slightly different fuels, so one may get you 300 miles the other may get you 350 miles.

There are plenty of reasons as to why your cars millage has changed/dropped...i am almost certain its not because there is a chip in the car that changes the fuel consumption based on the economy.

Same gas station each time. And I've tried to isolate virtually every factor that could be causing these drastic swings. It definitely lines up better to oil prices and the economy than it does the seasons.

To what some of the posters above mentioned, cars get worse mileage in the summer. You use your AC, the air is warmer and less dense (negatively impacting combustion efficiency), and summer fuel blends are less efficient on a volumetric basis (although more efficient on a thermal basis).

No check engine or other indicator lights on at all, I tend to take very good care of my car and never let an issue go unattended. Have never had any real problems this vehicle.

Also I know the same gas companies can change the same blend seasonally (and otherwise), but the wild swings I'm seeing both negative AND positive are pretty flagrant.

i'd get it on a rolling rig so you can test the cars efficiency at various speed so perhaps it drinks fuel like hell when you roll slowly through a jam at 15-20mph but when running at 50+ mph it sips the fuel alot better

also consider what is inside your car as carrying extra weight wont help

If you recall, MTBE was replaced by Ethanol by Congressional mandate because it was not only a carcinogen but it was found in our water supply.

I suspect what you are encountering is the increase in the amounts of Ethyl alcohol in lieu of MTBE in gasoline these days commonly known as E10....and I believe in some states they've even introduced more recently E15 which is 15% volume of Ethanol vs 10%.

Alcohol doesn't contain the same amount of energy as gasoline. So the more that's added to the gasoline mixture the less bang you get for your buck...

Plain and Simple.

www.epa.gov...

Originally posted by SirMike
To what some of the posters above mentioned, cars get worse mileage in the summer. You use your AC, the air is warmer and less dense (negatively impacting combustion efficiency), and summer fuel blends are less efficient on a volumetric basis (although more efficient on a thermal basis).

edit on 15-9-2011 by SirMike because: (no reason given)

SirMike, the fluctuations don't always fall in line seasonally, but that of course could explain a small portion of it. Also I've gone through great lengths to test exactly what you're talking about - for months at a time. I've gone exclusive AC for a time (even when it's cold), no AC at all for times (even in 100 degree weather), all windows and no AC (even in the rain...), etc.

Your local gas stations were supplied with gasoline with a higher than advertised Ethanol content.

Get used to it. It will become more common.

Originally posted by Ajax

Originally posted by SirMike
To what some of the posters above mentioned, cars get worse mileage in the summer. You use your AC, the air is warmer and less dense (negatively impacting combustion efficiency), and summer fuel blends are less efficient on a volumetric basis (although more efficient on a thermal basis).

edit on 15-9-2011 by SirMike because: (no reason given)

SirMike, the fluctuations don't always fall in line seasonally, but that of course could explain a small portion of it. Also I've gone through great lengths to test exactly what you're talking about - for months at a time. I've gone exclusive AC for a time (even when it's cold), no AC at all for times (even in 100 degree weather), all windows and no AC (even in the rain...), etc.

I did a lot of performance testing for combustion turbines and big marine diesels and if you really want to do this right, here’s how you go about it. You can find a relevant resource with ASME PTC 17. It’s a standard written for the performance testing of internal combustion motors. You can request a free copy through your library if you don’t want to pay for it.

In short, you will need to do the following:

1. fill up your tank
2. collect a sample of the fuel
3. send the sample out for testing
4. data log every minute you drive and record the following: speed, engine rpm, air temp, humidity, MAP flow data, altitude change, barometric pressure, auxilarly loads, etcetera
5. fill up your tank after a few hundred miles and record the amount of fuel used
6. find performance data on your motor
7. “normalize” all your data back to a reference point using the methodology in PTC 17 to find your overall corrected efficiency.
8. Repeat and compare with whatever

This wont be a “true” PTC 17 test, as that requires very specilized equipment, but good enough to validate your hypothesis if you follow the methodology.

reply to post by Ajax

Same gas station each time. And I've tried to isolate virtually every factor that could be causing these drastic swings. It definitely lines up better to oil prices and the economy than it does the seasons.

A lot of gas stations, especially locally-owned ones, buy their gas from a small distributor, which in turn buys from the lowest priced suppliers. So the same station may have completely different blends/octane ratings from one week to the next.

Check the octane rating labels sometime on the pump (not the signs, but the inspection stickers). They specify a minimum octane rating as opposed to an exact one.

TheRedneck