Squeezing Every Last Drop of Gas Mileage

[RoXXXanne13]

Alright, as we 1.8L owners know, we don't get the awesome mpg that the 1.4T gets. That being said, what I can do in order to get the BEST mpg?

Here's my driving:
I drive almost 2500 miles a month. I'd say at least 90% of that is highway. (60% is 65+ mph and 30% is ~55 mpg) The other <10% is stop and go, from 25 to 55 mph.

At the moment I am getting 29.5mpg, what can I do to ensure I am getting the absolute best mpg? What should my tire pressure me at? What gas should I use? What is the "sweet spot" for speed, when trying to get the best mileage?

I'm also open for modifications, but nothing crazy expensive. I'm trying to save a little money by getting better mileage, so I don't want to break the bank while trying to save it.

Any help is appreciated, thanks.

(Looks my Fuelly in my signature is different. My current mpg reported by my car is only the last 3 fill ups, while the Fuelly is lifetime.)

man i make a few trips to NY from NC a year if i can... i noticed my 5spd pulls about 3 grand at 73, so thats my sweet highway speed... anything over that is a cliff... like i made one trip at 75-85mph... was getting roughly 31.8... one trip 75ish 34, .... my personal favorite speed for these trips is 71, i seem to get optimal mileage while still clicking along at a speed i can accept, and i get 36.4.... thats about all she wrote... obviously, try and time red lights so you never have to stop, keep the air off the windsheild, and winsheild foot , those both cause the ac condensor to turn on, maintain tire pressure, i run mine at 38, hmmmmmmmmmmmm idk what else... also i only run 93 man since my first fill up, idk how other octanes will do, hope i could help

 

[Eric Smit]

if you go 65 it will be better.


-Eric Smit

 

[RoXXXanne13]

if you go 65 it will be better.


-Eric Smit

the ride to ny is long enough....

 

[HADES20]

Or you could just enjoy the engine and speed everywhere and pretentious the two is actually a 3

 

[inm]

Or you could just enjoy the engine and speed everywhere and pretentious the two is actually a 3

Pretending the 2 is a 3 won't help my bank account any. :sadbanana:

 

[Eric Smit]

Pretending the 2 is a 3 won't help my bank account any. :sadbanana:

you could look at your bank account and pretend the 2 is a 3 and the decimal is two spaces to the right.


-Eric Smit

 

[Chainsaw]

Average: 38.7 mpg (and climbing)

I've got the 1.8, 5 spd hatch with 2,677 miles on it now. When I first bought it, I thought I was doing good to get 30 mpg and that was sissy-footing. After the following changes, mods, I've been getting 38.7 from the last four tanks.
1. As little defrosting as possible - same for AC
2. "Brisk" warmup and drive off
3. Tires inflated to 40 psi
4. Don't waste any time climbing to 5th gear.
5. Engine revs are kept between 2k and 2,700. Every so often, I stand on the pedal to burn off anything that's built up.
6. El Cheapo CAI by Spectre tucked into wheel well, wrapped with HVAC tape.
7. Just put in synthetic 5-30, hoping it helps too.
8. I drive 120 miles/day, 50% hwy, 50% following slow locals and logging trucks over hilly terrain.
9. Clutch and gear disengaged when traveling down hills.
On the highway, I'm between 65 and 70, and on the rest, between 45 and 55, mostly 55. I plan to install a ground kit if I can gather enough evidence that it will reduce turbulence. Then again, it looks so cool, I might get it anyway. Hope this helps.

 

[mitdr774]

if you go 65 it will be better.


-Eric Smit

try 60 and enjoy even better economy. My best run was over about 700 miles with 30-50 of it city and the remainder was on the highway with cruise set to 60. Whole trip averaged 43.18mpg. No fancy driving techniques and the car was completely stock. Took about an extra 45 minutes to get where I was headed (about an hour and a half round trip). I will take over 40mpg compared to mid 30s on the highway.

Current work location and weather are destroying my average, but Im still beating the city rating even on a pure city fill up in these ****ty temperatures and weather conditions.

 

[inm]

I've got the 1.8, 5 spd hatch with 2,677 miles on it now. When I first bought it, I thought I was doing good to get 30 mpg and that was sissy-footing. After the following changes, mods, I've been getting 38.7 from the last four tanks.
1. As little defrosting as possible - same for AC
2. "Brisk" warmup and drive off
3. Tires inflated to 40 psi
4. Don't waste any time climbing to 5th gear.
5. Engine revs are kept between 2k and 2,700. Every so often, I stand on the pedal to burn off anything that's built up.
6. El Cheapo CAI by Spectre tucked into wheel well, wrapped with HVAC tape.
7. Just put in synthetic 5-30, hoping it helps too.
8. I drive 120 miles/day, 50% hwy, 50% following slow locals and logging trucks over hilly terrain.
9. Clutch and gear disengaged when traveling down hills.
On the highway, I'm between 65 and 70, and on the rest, between 45 and 55, mostly 55. I plan to install a ground kit if I can gather enough evidence that it will reduce turbulence. Then again, it looks so cool, I might get it anyway. Hope this helps.

How does it ride with your tires at 40?

Also, judging by #9, you have an MT, correct? Hopefully your tips will help me as well.

 

[$ub$onic]

I was told not to put in natural going down hills.

 

[Swordsmith]

According to my UG, and my gut feeling, I get better mpg with the clutch pedal on the floor than with it up. I'm not certain I'm reading this right, are you saying that if you don't need to use power to keep your speed up, that it still makes sense to leave the engine in gear and your foot off the clutch?

When I do that the car slows down faster and UG says it's costing me more gas while it's happening.... plus I have to spend gas sooner to get back up to speed.

UG thinks this is the difference between 50mpg and 300mpg during the coasting intervals. Now my UG is always reporting insane things to me about my mpg, ever since the Flexfuel conversion, but it used to be pretty reliable before I did that, and it was reporting the same things.

 

[Chainsaw]

To be honest, I could not tell one bit. I think it's the fact that they are 15s and not the dinky little 14" donuts I had on my Accent.

 

[Chainsaw]

Yes, I have the MT. Besides the things I mentioned, the car is bone stock.

 

[Eric Smit]

Swordsmith, you need to recalibrate your MPG for the E85 and you need to initially calibrate injector cutoff.


-Eric Smit

 

[Chainsaw]

According to my UG, and my gut feeling, I get better mpg with the clutch pedal on the floor than with it up. I'm not certain I'm reading this right, are you saying that if you don't need to use power to keep your speed up, that it still makes sense to leave the engine in gear and your foot off the clutch?

When I do that the car slows down faster and UG says it's costing me more gas while it's happening.... plus I have to spend gas sooner to get back up to speed.

UG thinks this is the difference between 50mpg and 300mpg during the coasting intervals. Now my UG is always reporting insane things to me about my mpg, ever since the Flexfuel conversion, but it used to be pretty reliable before I did that, and it was reporting the same things.

I was kinda surprised myself, but it seems that pushing in the clutch and taking it out of gear and letting it coast downhill (and I'm not talking long grades where I slow down so much I have to downshift) really helps. My speed doesn't drop significantly, probably because of the lower rolling resistance. Keep in mind, too, I'm not advocating any extreme hypermiling stuff-I stay in the speed limit range-plus or minus 5 to 10 mph.

Just for funzies, I plan to make a diffusor out of that area on the bottom of the bumper-that thing has got to catching some serious air. Has anybody done this?

 

[Eric Smit]

that rubber thing is a "diffuser" of sorts.


-Eric Smit

 

[ahtoxa]

Coasting in gear will under most circumstances engage DFCO (deceleration fuel cut off), as Eric mentioned and it will net infinite MPG as no fuel is fed to the engine and it is rotated by the inertia of the car.

Whether coasting in gear or in neutral is more efficient - that depends on your circumstance. If you're seeing a red light ahead or are anticipating slowing or stopping, then staying in gear is more efficient. However, if you want to maintain more speed, going into neutral may be more efficient as it lest you travel further vs. staying in gear (no engine braking).

That said, I'd stay in gear with the Sonic. Not sure on the 1.8, but the 1.4's compression braking is weak due to the small motor.

 

[Eric Smit]

great way to say it ahtoxa.


-Eric Smit

 

[ahtoxa]

I forgot to mention that DFCO will turn off (injectors will get fuel) right around 1100-1200 RPMs. Engine management will kick in to prevent stall.

I've also realized after I posted that with 1.8's 5 speed DFCO will engage at lower speed vs the 6 speed on the 1.4 due to 6th gear being taller than 5th.

I've watched DFCO behavior on mine via the Scangauge for a little while to confirm in regards to 1.4's engine management.

 

[inm]

Hmm, this is better than 29.5.

Sent from my Galaxy Nexus using Tapatalk 2