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Fuel Economy

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Tracy
#1
I want to compare MPGs. Today: 20.3 mpg Trip ODO: 30 miles. Total ODO: 10,300 miles.

A majority of my driving is around town. I don't speed, but I don't take my time getting to the speed limit either. Stopped at the crosswalk, I will often bring 2nd gear up to 5k rpm and skip 3rd and drop right to 4th, staying ahead of the pack, with only needing to let off the gas before the next light turns green, or try to. Often, traffic behind me feels the need to set me as the checkered flag, but I usually won't let traffic come crowd around me. I will maintain my distance, and perhaps just keep right as the rear of the pack plays leap frog with each other, fighting for position among other grocery getters and soccer moms. Otherwise, I make sure to stay in a staggered formation, leaving myself an out, and an opportunity for the vehicle ahead of me to change lanes if needed.

So, that has my City MPG around 18-24 mpg City.

My mixed City/Hwy mpg has been 27 mpg.

On the highway, I cruise in 6th at 70mph, which is the typical flow around here. I always get to highway speeds at WOT. No sense in wasting a good opportunity to check performance.

All Hwy miles: 34-36 mpg.

I drove from San Diego to Stockton on I-5 at 75 mph, with about 500lbs of gear maintaining 34 mpg. Empty miles heading south to San Diego got 36 mpg @ 80 mph (10 over)

Going up Highway 101 from San Diego got me 32 mpg, with some traffic and hills and some showing off for a passenger.

But I have taken it very very easy this week, hardly bring the rpms over 3k, going below the speed limit, smooth driving, and get the worst fuel economy. 20 mpg. I think that the short time I spent accelerating gives a longer time to just roll and that's where I save the most fuel In Town.
 


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Fairfax
#3
I read somewhere that accelerating quickly is actually more fuel efficient than slowly, as you spend less overall time wasting gas getting up to speed and more time in a higher gear once at speed. So I get up to speed quickly and then putt around like normal.

As for my MPG, I'm right where you are. My daily commute is 70/30 highway/city on the way to work, but 100% ~40mph on the way home (I take a less congested route home), and I've been averaging 27MPG so far. My car has ~2400 miles on the odometer.

My problem is that 4th gear is so versatile that I often forget to shift up to 6th a lot of the time when I cruise around at 45/50ish MPH on surface streets. I only remember to upshift when I look down and that up-arrow tells me to.
 


rodmoe

5000 Post Club
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#4
I wish we could hear crickets up nort here ... I was rollin avg 29 overall on the gauge in the dash, but reset my ECU with the latest COBB update just to be safe not know if it was needed so now I am rollin 25 all in town driving.. but doiing it the real way I got 28 on the last tank.. not bad considering the weather here has not been above freezing but twice in the last 3 months.. for a while there it did not get about ZERO F so MPG should get better if warmer weather ever gets here ..
 


OP
Matt_FiST
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Thread Starter #5
I read somewhere that accelerating quickly is actually more fuel efficient than slowly, as you spend less overall time wasting gas getting up to speed and more time in a higher gear once at speed. So I get up to speed quickly and then putt around like normal.
That makes sense. Less time accelerating = better fuel economy. Im also wondering if only filling my fuel tank half full will help give an extra MPG or two in town. And Fill the tank for highway trips to add weight to momentum. My semi will roll forever at 80k lbs. also get 8.5 mpg, with limited idle time. I try keep the idle time as low as possible in any vehicle I drive.
 


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#6
I filled up today and calculated 25.7 mpg by hand. Sounds about right since I beat on the car a lot during the warm weather this week. I love this car...
 


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El Paso
#7
That makes sense. Less time accelerating = better fuel economy. Im also wondering if only filling my fuel tank half full will help give an extra MPG or two in town. And Fill the tank for highway trips to add weight to momentum. My semi will roll forever at 80k lbs. also get 8.5 mpg, with limited idle time. I try keep the idle time as low as possible in any vehicle I drive.
By running half a tank, you're looking at a weight savings of 50-ish lbs. Im pretty sure that isnt going to make a noticable difference for gas mileage.
 


OP
Matt_FiST
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Thread Starter #8
By running half a tank, you're looking at a weight savings of 50-ish lbs. Im pretty sure that isnt going to make a noticable difference for gas mileage.
I might be able to save 0.1 mpg on a tank. ($100 per 100,000 miles)

$4 per gallon @ 20 mpg = $0.20 per mile. (0.1 mpg increase saves $0.02/mile)

100,000 city miles @ 20 mpg = 5000 gallons

$4/gal x 5000 gal = $20,000

Each 0.1 mpg increase saves $100 per 100,000 miles. (0.1 mpg = 0.5% of 20 mpg)

Each 0.1 mpg increase saves 0.5%. (0.005 x $20,000 = $100)

So if 0.1 mpg saves $100, 1 mpg saves $1000. (per 100,000 miles)

Am I right?



-$25,000 FiST @ 30 mpg = $35,000 per 100,000 mi @ $4/gal

-$5,000 lemon @ 15 mpg = $31,667 100,000 mi @ $4/gal

But you will probably have to buy 3 lemons before you get to 100,000 miles.
 


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307
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Location
El Paso
#9
Alright, so if you save $100 per 100,000 miles:
The average driver puts 14,000 miles on their car per year.
100,000/14,000 = 7.14 years
7.14 years x 12 months per year = 85.71 Months
Your $100 saved / 85.71 Months = $1.16

Congrats, you can buy yourself a pack of gum each month with all that dough you're saving.
 


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Fairfax
#10
Alright, so if you save $100 per 100,000 miles:
The average driver puts 14,000 miles on their car per year.
100,000/14,000 = 7.14 years
7.14 years x 12 months per year = 85.71 Months
Your $100 saved / 85.71 Months = $1.16

Congrats, you can buy yourself a pack of gum each month with all that dough you're saving.
But then figure the extra time you're wasting at the pump every half tank. Not worth the savings IMO. :p
 


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0
#13
I read somewhere that accelerating quickly is actually more fuel efficient than slowly, as you spend less overall time wasting gas getting up to speed and more time in a higher gear once at speed. So I get up to speed quickly and then putt around like normal.

As for my MPG, I'm right where you are. My daily commute is 70/30 highway/city on the way to work, but 100% ~40mph on the way home (I take a less congested route home), and I've been averaging 27MPG so far. My car has ~2400 miles on the odometer.

My problem is that 4th gear is so versatile that I often forget to shift up to 6th a lot of the time when I cruise around at 45/50ish MPH on surface streets. I only remember to upshift when I look down and that up-arrow tells me to.
I find myself doing that too. I think the up arrow comes up a little early/often for my taste lol.
 


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132
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7
Location
Calgary
#14
I wish we could hear crickets up nort here ... I was rollin avg 29 overall on the gauge in the dash, but reset my ECU with the latest COBB update just to be safe not know if it was needed so now I am rollin 25 all in town driving.. but doiing it the real way I got 28 on the last tank.. not bad considering the weather here has not been above freezing but twice in the last 3 months.. for a while there it did not get about ZERO F so MPG should get better if warmer weather ever gets here ..
I've been getting 8.4 litres/100km which is exactly the same as you, Rod. Lots of cold starts (some really cold) and a combination of city and lower speed divided roads.
It's a treat to go fill this up and only pay $35 compared to the $100+ for my Yukon XL.
 


rodmoe

5000 Post Club
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wausau
#15
I've been getting 8.4 litres/100km which is exactly the same as you, Rod. Lots of cold starts (some really cold) and a combination of city and lower speed divided roads.
It's a treat to go fill this up and only pay $35 compared to the $100+ for my Yukon XL.
Yup I don't like filling up the Avalanche either cuz when we do it most times to haul the trailer someplace and then it gets maybe 9 mpg pulling instead of the always delightful 12-14 mpg empty LOL and thats with a little V8..
 


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Holmdel
#16
Its wierd I find if I reset my mpg while driving it updates like every 5 seconds,but if I don't it only updates often and is kinda inaccurate. Example, everytime I get in car for work in the morning and put it on the mpg reading,it stays low and only changes often,but if I reset it by pressing and holding the button in on the turn signal handle until the dashed lines stop,then my mpg climb rapidly and changes/readjusts like every 5-10 seconds. So I guess if you want an accurate reading you gotta reset your mpg reading everytime you get in the car and drive. [screwy]

I now have 1300miles and if I keep it in 6th at 70mph I can see 33mpg,but usually I'm doing 80 and see 28-29. Around town,forget it,I'm usually flooring it around everywhere and seeing 25mpg. Hoping it gets a lil better with warmer weather. Still I'm satisfied though,cost exactly $40 on super for me to fill up.

-ry
 


Shmi

Member
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Fairfax
#17
Its wierd I find if I reset my mpg while driving it updates like every 5 seconds,but if I don't it only updates often and is kinda inaccurate. Example, everytime I get in car for work in the morning and put it on the mpg reading,it stays low and only changes often,but if I reset it by pressing and holding the button in on the turn signal handle until the dashed lines stop,then my mpg climb rapidly and changes/readjusts like every 5-10 seconds. So I guess if you want an accurate reading you gotta reset your mpg reading everytime you get in the car and drive. [screwy]

I now have 1300miles and if I keep it in 6th at 70mph I can see 33mpg,but usually I'm doing 80 and see 28-29. Around town,forget it,I'm usually flooring it around everywhere and seeing 25mpg. Hoping it gets a lil better with warmer weather. Still I'm satisfied though,cost exactly $40 on super for me to fill up.

-ry
It averages over time, the longer you drive without resetting it, the less each new reading affects the average. That's why it adjusts quickly after you reset it but seems to slow down over time.

For example avg of 5 and 10= 7.5. Avg 5+10+10= 8.33, 5+10+10+10= 8.75. As you keep adding a number to the pool, the effect/change on the average become less significant.

Anyhow I managed 34 mpg at 60 mph today. Probably the best I'll get for now.
 


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307
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17
Location
El Paso
#20
It averages over time, the longer you drive without resetting it, the less each new reading affects the average. That's why it adjusts quickly after you reset it but seems to slow down over time.

For example avg of 5 and 10= 7.5. Avg 5+10+10= 8.33, 5+10+10+10= 8.75. As you keep adding a number to the pool, the effect/change on the average become less significant.

Anyhow I managed 34 mpg at 60 mph today. Probably the best I'll get for now.

Thank you for this. Reading his post was hurting my logic bone.
 




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