The 'fuelly' economy thread

[Darlo]

I went up to 41.3 on my first full tank of 89oct e10 after my 5spd swap. I don't drive the car easy, so I'm pleased with the results. If only I could get non ethanol fuel I'd easily get 3-4 mpg more. I hate E10!


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Even if there is 10% ethanol, you will only see an increase of 4.2% or about 1.7mpg. This is because ethanol burns at 60% as efficient as "regular" gas. so at 90% gas and 10% ethanol, this would mean that the new mixture that burns at 96% as efficient. FUN FUN FUN!

[Click_It]

I use ethanol-free fuel so I can't even blame that. I figure I'll look at the quick fixes first and change the air filter and ignition leads which are both long overdue anyway, then maybe look at the fuel pump and go from there...

[rollertoaster]

I guess you are right about that. I have and have had turbo cars that suffered more of an economy loss due to E10. I guess it's due to the 11:1 air fuel ratio under boost


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[Larry Hampton]

Even if there is 10% ethanol, you will only see an increase of 4.2% or about 1.7mpg. This is because ethanol burns at 60% as efficient as "regular" gas. so at 90% gas and 10% ethanol, this would mean that the new mixture that burns at 96% as efficient. FUN FUN FUN!

Nope. In my '03 4.0 SportTrac when I run 100% gas I get an average of 400 miles to the tank. With E10 I average 350 miles to the tank. That's 12.5% worse. E10 is 10 cents cheaper that 100% so it actually costs more money to run E10. ($3.59 vs $3.49 currently)

[Zanzer]

have you calculated the percentage difference between these and stock? Your Speedo will be off so you may have been calculating your mpg wrong.

Example in my case I have 13's that are 7% larger so I have to multiply my total miles by 1.07 then calculate my MPG

I thought my car seemed a bit off. I forgot to factor in the change to 13" tires and Metro rims

Although, I went back and tried to recalculate my fill-ups taking this into consideration and now I have my Fuelly profile all screwed up LOL :blackeye:

Math > me @ 3am

[neanderpaul]

Going from 12" to 15" wheels WRECKED my mpg and yes I factored in the difference using the GPS trip. I went from 38 in town to 30 on the hgwy.

[Zanzer]

^^ Yikes! :shock:

That almost makes me wanna stick with 12's!

[Click_It]

Going from 12" to 15" wheels WRECKED my mpg.

Unfortunately for me my mpg has been this way for as long as I can remember even back on its stock 13" wheels (13" stock in Australia) but in saying that I didn't know any better until noticing the fuelly signatures on FF, it was then that I begun to realise my economic car isn't as economical as it should be. Though I'll be keen to see what my first tank on 15" wheels comes in as, so far just under half a tank and it seems to be drinking it at the usual rate.

I should find out what kind of mileage the other aussies on FF are getting too.

[200KGPGTP]

I'm getting 40+ consistently on my paper route.... Which is even worse than city driving.

My Fuelly is doing something funky. My signature number is different than my figure on the actual site..... what am I doing wrong? Lol

[Pu241]

My Fuelly is doing something funky. My signature number is different than my figure on the actual site..... what am I doing wrong? Lol

Looks OK to me.
Your badge shows an average MPG of 36.3 and the fuelly site, when I go to your link shows:

Basic Stats
36.3
(+0.4)
avg MPG

43.0
(+2.3)
last MPG

43.5
(3/23/11)
best MPG

All seems in order to me.

[TominMO]

I recently set up fuelly (had records dating back 12 months thus the 14 fill ups) and the first thing I noticed is my economy is considerably behind my american counterparts. I'm trying to understand why this is. I live in a hilly area and most of my driving currently is shorter city trips with little highway mileage so this is obviously playing a role. I don't drive hard, I coast in traffic where possible. My B3 is carby, is that also playing a big part? Despite the disadvantages above I still feel I should at the very least be achieving mid 30's. Surely you guys aren't just doing easy highway miles so something is wrong at my end.

Extreme mods aside what might be a few things to look into? I recently changed the fuel filter. Have tried cleaning up the carb, even running injector/carb cleaner through the tank. New spark plugs (although still running old leads), haven't touched the fuel pump yet. Any suggestions welcomed.

I'm sure it's a combination of things:
1. Carbys will get worse mileage due to less-precise fuel metering; you can improve both power and MPGs with a Weber carb though.
2. Hills and city driving. Can't do too much about them unless you move. But you can try hypermiling techniques to help out. Coasting is a part of that, but there is more you can do. http://www.hypermiling.com/car-mpg.html
3. Heavier wheels/tires require more energy to get moving from a stop, so here is another way you are taking a hit with city driving. On the other hand, on the hwy you should get better mileage since they are taller and so will raise your overall gearing.
4. Make sure your rear bearings and brake shoes aren't too tight.
5. Do a complete tuneup--disty cap, rotor, plug wires/leads.

[neanderpaul]

Many carbys have reported 48-49 mpg even with ac on.

[Darlo]

My Fuelly is doing something funky. My signature number is different than my figure on the actual site..... what am I doing wrong? Lol

You probably have your own fuelly set to "UK" and your sig is in "US". You would see a difference then.

[Darlo]

I just entered in my last one, and went 545kms in only 26.918 liters (338miles in 7.111 gallons (US)) For a grand total of 47.6mpg!

[Click_It]

Possibly a bad habit I have is idling the car before I go out, especially in winter I will let it idle for minutes sometimes as I brush my teeth etc. It's a habit I've had since my very first car but maybe all this is doing is chewing fuel excessively. How long do you guys let the car warm up before driving? (I'm carby not EFI)