The quest for 500miles on single tank of gas

blinkz0rz

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I hypermile on my daily commutes, which yes I understand is absurd to do while owning a Si lol.

So I have posted before about how great my mpg is, averaging 44mpg usually. I am now deciding that I would love to hit the 500 miles mark while only using <11 gallons of fuel. I usually drive about 250-420 miles before filling up, based on my commutes and times especially for work.

My daily work commute is 52 miles, consisting of about 10 stop signs, no lights, and 95% country roads. The average speed is 55mph, and I usually set cruise at 57mph. Outside of my work commute, I don't usually go into town mainly because of the COVID. However I still drive easy when I do go into town for food or goods.

My driving style is mainly 30% throttle on acceleration, shifting usually between 2000-2500rpms, engine braking for stops and engaging the clutch around 800rpms to keep it from dying.

I also daily the TSP1 tune, because I have found out that my driving style has increased 2mpg compared to stock tune. Last summer I was getting about 42-44mpg on that stock tune, and with TSP1 it averages 44-46mpg. I believe it is due to the way that Derek has modified the fuel delivery and turbo in the tune. The boost is usually 10psi at the time of my shifts.

My mods are listed in my sig, but mainly it is just the PRL Cobra street and TSP1 tune.

I wonder if Derek has a tune for pure gas efficiency. I know a major mpg tune would greatly help the car reach that 500 mark. The highest miles that i have reached on a single tank was 470, but this was also during the stock tune. Lately the car has been displaying 505miles left to empty right after a fill up.

So, lets have some [green] fun!


EDIT: I achieved the goal! Check out page 3 for the pics.

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blinkz0rz

blinkz0rz

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Sidenote, I have reached 600miles on a single tank in my 2015 Accord. I was on a road trip vacation to Colorado/Utah for a week and on the way back I hit the 600 mark with about 7 miles left until E. I averaged 560miles during that entire road trip. I dunno if I still have that photo of the achievement.
 

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This is the closest I’ve gotten... I could have stretched it out another 80 miles...

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arpypat

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Sidenote, I have reached 600miles on a single tank in my 2015 Accord. I was on a road trip vacation to Colorado/Utah for a week and on the way back I hit the 600 mark with about 7 miles left until E. I averaged 560miles during that entire road trip. I dunno if I still have that photo of the achievement.
I believe that. I mean it does have a 17+ gallon tank! You'd get well 700 miles on your Si if it could hold over 17 gals of fuel!

Do you have the v6 accord? My stepdad has a 2015 EX-L, and IIRC, those have the cylinder deactivation when cruising on the highway.
 
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blinkz0rz

blinkz0rz

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I believe that. I mean it does have a 17+ gallon tank! You'd get well 700 miles on your Si if it could hold over 17 gals of fuel!

Do you have the v6 accord? My stepdad has a 2015 EX-L, and IIRC, those have the cylinder deactivation when cruising on the highway.
No, it was the 4banger tho. I got rid of the car in 2017.
 
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blinkz0rz

blinkz0rz

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I'm already getting better mpg running the TSP1 tune (which I find ironic), but if a different tune can improve the gas mileage I really wanna try it out. I'm looking for a daily green goal, I won't be racing the car in the new tune. Hell, I barely get the car past 10psi using the TSP1 tune on my daily work commutes.
 
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JO3L

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I found that the Honda computer is usually generous by about 1 mpg extra vs the calculated one in the Fuelly app.

Best I got was 332 miles out of 9.9 gallons for a 39 avg mpg. That was cruising at 80-90 mph mostly on the highway. One day I’ll do another road trip in the Si and make it into 40s.

Good luck on the quest to 500 though. I’m thoroughly impressed with your results thus far.
 
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blinkz0rz

blinkz0rz

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A little closer to the mark, but I pulled off 470 miles. I also learned that the car has more than a 11 gallon fuel tank.

So by doing the math from the pictures it comes down to 41.77mpg. I swear I only do full fill ups and usually get 10.5 gallons on a fill up, but today I was able to push it farther towards empty on my normal commutes.

Regardless, I am getting way better mpg than the dealership sticker of 28 city, 38 highway. 32 combined. Lol

Also just found that this government fuel economy page states the tank is 12.4 gallons. Hmm....

https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=39569

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arpypat

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The car has a 12.4 gal tank, but the low fuel warning comes on when there is less than 15% (~1.8 gal) left.
 
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blinkz0rz

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The car has a 12.4 gal tank, but the low fuel warning comes on when there is less than 15% (~1.8 gal) left.
Makes sense. I know they engineer the tank to be bigger than the notification suggests just so people don't actually completely empty the tank. I have done that in the past on my old 1988 Cutlass Calais.
 

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The best I did was around 500 miles in my old TLX. It was surprising to me how well they've gotten that V6 to be fuel efficient.
 

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You mentioned cruise control. I generally find cruise lowers my MPG as i can adjust the gas pressure better than the engine can when dealing with hills. As in, i can let the car slow down a little for an uphill, and then let it coast more down hill, thus gaining speed where as the cruise would rev the engine to make speed up the hill, and then slow down for the down hill.

Granted i dont know if you area is flat or not.

I am generally getting 38-44 mpg on my drives, but i hardly drive right now with COVID as i am working from home (so thankful for that). My normal commute to work was a 90 mile round trip and depending on when i left my house, it could be mostly 75mph on the highway.. or that annoying SPEED UP to 65; then slam on the brakes for no reason... 20mph crawl where you worry about getting rear ended, only to speed up again to 65 - rinse and repeat.

i have been thrilled with the MPG. i have a honda ridgeline and i get 18-22 out of that - so getting 40 or more out of the civic is just great! Honestly.. the SI checks every box.
 
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blinkz0rz

blinkz0rz

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@wintercast yeah I live in the flat farmland of Illinois. There is really one hill and the speed limit is 30mph on that so I just go easy throttle in 5th gear at 40mph up that.
 

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Premium... and premium plus? What octane are those options?
 
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blinkz0rz

blinkz0rz

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Premium... and premium plus? What octane are those options?
91, but the gas station dropped 91 Alcohol Free for 93 this week :D . I just filled up with 93 so I will see how that makes a difference this time.

Sadly, that now means I don't have alcohol free gas to use on my 72 Roadrunner. 😠
 
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