Gas mileage?

[robsander]

I figured manual was the only other logical reason but how about the difference in sedan vs hatch? And auto and manual for both? Perhaps there's already a thread for that with some numbers or data? Mind you I'm stock tune and mods and I understand that most ppl on here who log and check fuel trims and tables etc. Might not have info that would directly apply to my car being stock but.. hey you never know.

10.27 1/8 mile

 

[SuperFudd]

1.8 Auto LT Sedan, California.
When I bought mine new last December some on the lot were 37mpg and some including mine were 35. Apparently the 35s run cleaner due to extra anti smog stuff.
For the last 2 weeks I have been driving round trip between San Leandro and Union City CA once each day. 12 miles each way with 10 freeway. I reset the average mpg upon entering the freeway (I-880) and note the mpg as I get off. I have had no problem getting at least 45 mpg. I got 50 a couple of times.
It looks like the mpg increases 2 or 3 once the engine is warmed up.
Ambient temperature 68 - 75 F.

 

[Eric Smit]

I figured manual was the only other logical reason but how about the difference in sedan vs hatch? And auto and manual for both? Perhaps there's already a thread for that with some numbers or data? Mind you I'm stock tune and mods and I understand that most ppl on here who log and check fuel trims and tables etc. Might not have info that would directly apply to my car being stock but.. hey you never know.

10.27 1/8 mile

no difference for sedan and hatch, auto is lower than manual.

 

[Hdmanny]

I read on here somewhere that the hb are not are aerodynamic as the sedans. The best I have gotten so far is 38.4 mpg driving to work about 63 miles, combined city and highway driving. It dropped .2 when I got off the highway for the last few miles.

 

[Swordsmith]

The sedan is a little more aerodynamic than the hatchback, but it is also a little heavier. Looking at all the people reporting mpgs over the couple years Sonics have been driven in the real world, we haven't seen any real difference between the body types, I surmise this is because the two offset each other.

If this is the case, I would expect the sedan to be worse in short trip/many stops travel and the hatchback to be worse in long trip/high speed travel.

To get really good mpg, though, the trick is to travel at moderate and steady speed (45-60, few stops), which means neither of the two factors would affect mpg much.

 

[shorebreeze]

I figured manual was the only other logical reason but how about the difference in sedan vs hatch? And auto and manual for both? Perhaps there's already a thread for that with some numbers or data? Mind you I'm stock tune and mods and I understand that most ppl on here who log and check fuel trims and tables etc. Might not have info that would directly apply to my car being stock but.. hey you never know.

10.27 1/8 mile

Auto versus manual is affected significantly on the turbo at least by gearing. It's about an 8.8 percent difference in 6th gear (as in the car is turning over 8.8 percent higher RPMs on an automatic transmission than on a manual at a given rate of speed in 6th gear) -- which almost exactly accounts for the difference in EPA highway figures. In practice if you're in very flat territory this will be quite significant, whereas if you're in relatively hilly areas the slightly shorter gearing on the automatic will help. For my taste the gearing on the auto is OK for freeway driving, but a 7th gear wouldn't hurt. Going up those long hills on, say, I-94 in Wisconsin, the auto doesn't downshift but you might need to on the manual. Driving an auto on the flats of northern Illinois, however, is just a subsidy to ExxonMobil. And as strong as the torque on this engine is, I have to wonder why they geared 6th as short as they did on the auto. 2350 rpm at 70 doesn't sound like much but on this engine it's almost overkill. The manual's 2150 or so rpm is a better fit for freeway driving, at least to me. You RS folks may beg to differ. opcorn:

The turbo auto has its own secret mpg weapon, however -- with the stock tune and under a light right foot it will shift into 5th gear at 30mph, at a ratio that's between the 4th and 5th of the manual. I'm finding this helps tremendously on city driving, where I'd have to stay in 4th on the manual because of how long even 5th gear is. It won't help much though if you live in a state where the typical city speed limit is 25 and that speed limit is enforced . . . then you're in 4th for all practical purposes, and the 4th ratio on the manual is a slightly better fit.

 

[shorebreeze]

1.8 Auto LT Sedan, California.
When I bought mine new last December some on the lot were 37mpg and some including mine were 35. Apparently the 35s run cleaner due to extra anti smog stuff.
For the last 2 weeks I have been driving round trip between San Leandro and Union City CA once each day. 12 miles each way with 10 freeway. I reset the average mpg upon entering the freeway (I-880) and note the mpg as I get off. I have had no problem getting at least 45 mpg. I got 50 a couple of times.
It looks like the mpg increases 2 or 3 once the engine is warmed up.
Ambient temperature 68 - 75 F.

You sure that isn't just the 37 for the 1.4 turbo auto vs the 35 for the 1.8 standard auto?

 

[SuperFudd]

I am sure.
Has the gas formulation changed here to a lower mpg "winter blend" in the last week or so?
For the last 3 days I only get 40mpg rather than the previous 45+ mpg.

 

[mja]

I am sure.
Has the gas formulation changed here to a lower mpg "winter blend" in the last week or so?
For the last 3 days I only get 40mpg rather than the previous 45+ mpg.

I think the summer months for regulating vapor pressures are May/June-mid September, depending on the state/county, so yes.
Volatility/Reid Vapor Pressure (RVP) | Fuels and Fuel Additives | US EPA
Guide on State Summer RVP Standards | Fuels and Fuel Additives | US EPA

 

[mja]

Put simply NO.

The parts that aren't nitrogen are for the most part smaller in molecule size (like finer sizes of sand or rock) and will 1. slowly permeate, aka leak thru rubber....... OR if you never check your tires it will eventually go flat and 2. are more susceptible to changes in temp. Which as we learned in chemistry as a gas changes temps it increases or decreases in volume. Confined in a sealsed space means cold temp = less volume, increase in temp = more volume..................... no volume in a tire = flat tire.... lots of volume = really really inflated tire.


So the benefit of "Nitrogen" is that it leaks thru the tire substantially slower than air, meaning if you suck at maintenance your tire's will stay inflated way longer.....

...

Another benefit of nitrogen is it is inert which again we learned in chemistry class means less susceptible to temperature, and other scientific crap. Real world this means it tire psi doesn't go up and down with temperature changes....................... Which is HUGE in the winter, people that don;t check their tires usually have under inflated tires during cold snaps. Which of course means worse MPG and tire wear...

good post, I've always wondered how we came to see the nitrogen tire inflation gimmick in the real world. Must have been from formula one or some racing events trickling down to the luxury-cruiser daily driver/track day crowd and now implemented as a sucker buck scheme by manufacturers and tire companies. I've seen some places charge 20$ for nitrogen in the tires. I wish I was a salesman opcorn:

After reading all of that and thinking it over, I think the only sane point of nitrogen use in a street driven tire is that it does not oxidize the rubber or the wheels over time. With as many bumps and weather changes as a daily driver sees, I hardly suspect nitrogen holds pressure much longer than air. Supposedly it makes steel wheels and tire polymers less susceptible from rust or oxidation respectively.

The nitrogen thing makes no sense to me because, 1- most wheels are alloy now, 2- I've never seen steel wheels with mounted tires rust inside the tire mount lip, especially to the point of compromising the integrity of the steel, 3- the tread on the tires will be worn down from friction before the rubber is oxidized from the inside, and even then it'll be oxidized from the outside, we've all seen surface cracks 'tire rot' on old tires.

I guess if it's free and readily available, wouldn't hurt.

 

[mja]

The turbo auto has its own secret mpg weapon, however -- with the stock tune and under a light right foot it will shift into 5th gear at 30mph, at a ratio that's between the 4th and 5th of the manual. I'm finding this helps tremendously on city driving, where I'd have to stay in 4th on the manual because of how long even 5th gear is. It won't help much though if you live in a state where the typical city speed limit is 25 and that speed limit is enforced . . . then you're in 4th for all practical purposes, and the 4th ratio on the manual is a slightly better fit.

Anyone know the stall speed of the auto's torque converter? if the rpm's are below the stall speed, slippage = not as magical of a weapon

 

[ChrisJ]

Anyone know the stall speed of the auto's torque converter? if the rpm's are below the stall speed, slippage = not as magical of a weapon

And if this was the 1970s before lockup converters that would be true.

I'm sure the Sonic's 6 speed auto locks the converter up in 5th gear. Just a guess, but I'd guess the stall speed is likely around 1400rpm. You can find this by holding the brake and giving it throttle until the tach stops climbing, only for a very brief period of course.

 

[robsander]

Its around 2800-3000 with Tcs on and a bit higher, like 4200 or close to it with tcs off

10.27 1/8 mile

 

[ChrisJ]

Its around 2800-3000 with Tcs on and a bit higher, like 4200 or close to it with tcs off

10.27 1/8 mile

There's no way.

First TC wouldn't effect it and secondly just no.


You were stopped when you did this test? Sitting still, with your foot firmly on the brake you give it throttle until the tach doesn't want to climb anymore without forcing the car to want to move. That's the stall speed.

There is no way it's 3000-4200.


* EDIT. Doesn't the 1.4T equipped Sonic put the transmission into neutral when stopped? I'm going to guess that's why the test isn't working. Your foot is on the brake so the transmission is in neutral and the ECM is limiting the rpm rather than the torque converter.

 

[shorebreeze]

With 2450 miles on the clock, distributed as about 1750 highway and 700 city, I'm running a total of 35 mpg Onstar (so I would suspect 33 to 34 calculated) on my 1.4 turbo auto. This on 87 octane through about 2200 miles and 93 since. The 93 is starting to look as though it significantly boosts urban mpg, although driving technique is a factor as well because I only figured out in the past 300 miles or so that getting the car to 30mph quickly and then holding it there was a very quick way of getting it to shift into fifth gear and stay there. In heavier traffic I have to settle for the fourth gear shift point instead.

We'll keep things simple like this until the next big tuning sale, and then I'll consider my options again. But I also plan to add a bit of weight by way of some Dynamat.

 

[ahtoxa]

There's no way.

First TC wouldn't effect it and secondly just no.


You were stopped when you did this test? Sitting still, with your foot firmly on the brake you give it throttle until the tach doesn't want to climb anymore without forcing the car to want to move. That's the stall speed.

There is no way it's 3000-4200.


* EDIT. Doesn't the 1.4T equipped Sonic put the transmission into neutral when stopped? I'm going to guess that's why the test isn't working. Your foot is on the brake so the transmission is in neutral and the ECM is limiting the rpm rather than the torque converter.

Oh, wow. 4000 stall will never be found on a street production car. Not that I'm aware, at least.

around 1500 is generally where factory stall would be.

 

[robsander]

I actually spoke without really thinking it through. My idea of the stall was different I was mistaken between two ideas. Thanks for clearing that up for me.

10.27 1/8 mile

 

[shorebreeze]

* EDIT. Doesn't the 1.4T equipped Sonic put the transmission into neutral when stopped? I'm going to guess that's why the test isn't working. Your foot is on the brake so the transmission is in neutral and the ECM is limiting the rpm rather than the torque converter.

Not by my observations. The fuel flow when stopped at a traffic light runs about 0.23-0.24 gallons an hour, and immediately drops to 0.19 or 0.20 when you shift into neutral. 1.4 turbo automatic.