It's generally considered that higher octane fuels give better performance and mileage, but are usually more expensive. Sadly there's nowhere local I can get any, but I have tried a tank in the past and it performs better overall.
I think I'm gonna give the mid grade 89 octane a try.
I checked. There's more than one station selling the mid grade cheaper than what I'm paying for regular.
I also have to admit. Maybe it's because of the ethanol. I have sat with my car idling for a few minutes. Longer than I would like to save gas. It got to where it was idling with a little vibration. Not the super smooth I'm used to. I rationalize that as the engine trying to ping. But the computer stopping it. Rationalizing it's fighting pinging. ????
I am impressed at the compression ratio. It's 10:1. That's pretty high while burning regular. Computer must be doing a bunch.
I've considered Premium. Also the Premium is easy to find with no ethanol in it. Cost is considerably higher. Which causes me a big hesitation to try it. That is also why I posted this thread. Hoping for feedback from people who have tried.
In times past when I have tried higher octane gas I have found that the improvements in fuel economy are diminished by increased cost of high octane. I stay with regular, unless the manual calls for high octane.
Higher octane in itself will not gain you better mileage, unless the engine was designed to operate on high octane fuel. The larger variable is the ethanol content. Generally, to get the best mileage use the octane rating that is called for in your vehicle owner's manual.
I just checked a station that doesn't have the best prices. But they're not bad. This station has Regular without ethanol.
89 octane mid grade.... $1.88 a gallon
87 octane Regular......... $2.38 a gallon (no ethanol)
93 octane Premium...... $2.58 a gallon (no ethanol)
That's quite a difference. Right now I have 87 Regular with ethanol in it.
As stated, higher octane doesn't help unless the engine is designed for it. There is a chance that the owner's manual may not be telling you what that octane actually is, but what the marketing department thinks is best to sell that particular car.
Take the 1.4L turbo in my Sonic. It is an European designed engine, and it can make use of higher octane fuels. It does get better fuel economy on mid grade and premium, along with more power produced, but it usually isn't enough of an improvement to cover the typical price difference in fuel here.
I don't know if the foreign Aveo is labeled for regular gas or not. I do know the rest of the first world's regular gas is higher octane than the USA's, and anything higher than regular on the window sticker hurts sales of everything that isn't a luxury performance car.
The best place to find out if that Corolla's engine can make use of higher octane would likely be a model specific forum.
Ethanol has less energy per volume than gasoline, so it will lower fuel economy. It does have a higher octane though, so some of that lost could be gained in a high octane engine.
Odd that that station has no ethanol in the regular and premium, but not the midgrade. I thought midgrade was mixed from the regular and premium at the pump.
Some stations have "blender" pumps, that mix it as it is dispensed. Other stations have a separate tank. When I worked for a fuel station our "midgrade" was 1,000 gallons of 87 octane + 200 gallons of 93 octane, and all dumped into the same tank.
For around here. The unusual part is the Regular with no ethanol.
Now the Premium. Many stations advertise no ethanol in the Premium. Why? Those who buy Premium. If there is ethanol in it. They throw their terrible two's fits and all.
I burned mid grade in my last car. The reason was, when gas prices were high. The mid grade was the cheapest, period. I did notice that car had to make adjustments going from regular to mid grade or back. Took it the better part of a tank to make those adjustments.