Easy 5mpg gain in FE (due to switch to summer gas?)

[Green Machine]

Well my Aveo is finally living up to some of its FE ratings. My last two tanks have gone up from almost 32mpg average to almost 37mpg average. I've never had 37mpg in ANY tank so far.

So, what made the difference? Around this time of year, my area stops using oxygenated fuel.

I wonder if the benefit of using oxygenated fuel (OF) is still attained after you factor in the resulting loss in FE. As I understand it, OF was primarily meant to help emmisions on carburated engines. If this is true, I wonder if it is still necessary to use OF since the majority of cars are now using some form of TBI or EFI and the computer is watching emmissions via the 02 sensor.

Tommorrow I'll see if the MPG increase stays consistant while doing some heavy highway driving.

Any thoughts?

[Lazarus]

That's a 15% increase if mileage. Oxygenated fuel is not going to give that much of a decrease. Most info has it at 1-3%. Nice job with the Aveo.

[Green Machine]

I'm wondering if there is some attribute in the Aveo that makes it suffer more an MPG decrease than the average car. I haven't had it very long and have never seen what it does with non-oxygenated fuel. Even my SGII was thrown off by the change. Since I got it dialed in, it was pretty correct about how much gas the car needed at fuel up time. Usually, I put in a tad more fuel than it expects and have to correct the SG upward a tiny bit.

This time, I put in slightly more than a gallon LESS fuel than the SG expected and had to correct it downward. I've never had to correct the SG this much.

We'll see if the MPG holds or not. Maybe it's just a fluke.

[Lazarus]

Was the gas from the same station?

[Green Machine]

The 2 tanks in question were from the same station. But it isn't the same station(s) I normally use. It just happened to be the handiest station both times.

Ordinarily, there are only 2 stations that I use and I use the same pumps at both.

[igo]

The warmer temps will also increase your mpg (unless you turn on the AC).

[cfg83]

Green Machine -

If your hypothesis is true, then I think you'll have to wait until they change the fuel back, . If your MPG goes back down, then maybe you should look for an aftermarket "oxygenator" additive (does that even exist?!?!?!?).

But, like everyone else says, the weather has a big effect. Can you describe the recent weather you have been experiencing? Does it coincide with the MPG change?

CarloSW2

[homeworkhome53]

I've read many internet post about poor milage with the Aveo, but am happy with mine. Bought new in Feb (Very cold, heavy snow) the first tank was 32.8mpg and the last thank was 43.1 each has gotten better by observing what i've learn here. I have a 53 mile round trip daily commute. I've slowed down and add about 7 minutes (each way) to my travel time. The weather has improved and that seems to be having an effect but there was still snow on the roads when the first tank went over 40mpg. I think the biggest detriment to fe is speed. The SG often hold a stable mid 50's when obeying the posted speed through two small communities I have to go through. Which has encouraged me to set back and enjoy the ride on some lonely back roads, that and the $3.70 a gallon on the sign at the local rural gas station. It is a pleasant little bare bones car with a good radio. I'm getting to enjoy classical music. It goes with the more sedate mood. If someone wants to pass I slide to the right. It their gas and their life. Not my problem.

homeworkhome53