which grade of gas are you using?

I've experimented with 87, but the car doesn't like it a whole lot once temps get warmer outside. It bogs from a standstill quite a bit with the AC on. I have found that it likes 87 from the Exxon up the road, but other times I've tried it, it ran like complete crap on other brands. Hesitation was seriously bad.

I usually use 89 octane and feel that my (untuned) Cruze performs just fine on it, or in the peak of summer when it's 90-100 out, I'll use 93. Same reason...that bogging with the AC on is due to timing being pulled because of pre-detonation. It can be downright dangerous trying to pull out into an intersection and the car just won't respond like it normally does.

For me, there is no noticable MPG difference between 89 and 93, but there is a ~4 highway MPG difference between those crummy 87 tanks and 89.

chevycruze2012 said:

Well I used to put 87 octane in my 05 cavalier when I had it 2 years ago and I noticed it helped the mpg a little. Not by much but it did. I was going to fill my car up today with the 87 octane but then I was thinking.."Im not sure how well it will run for sure or if my mpg will increase or decrease". Can anyone tell me with their knowledge and/or experience, in comparison, which fuel burns the best to get better fuel economy? I want to see how much more mpg I can get out of my LT. I think right now, im getting 38-39 mpg going right at the speed limit=]

Click to expand...

Try a tank of each on your car and see how it does. It mostly depends on your driving...I'm a bit heavy-footed and so I'm sure I'm throwing away MPG on 87. The car feels a bit slower, so I push it a bit harder. If you drive conservatively all the time, there may not be a difference.

Turbo engines aren't a fan of low octane gas, so they pull timing and decrease power when they detect knock. This happens often on the Cruze - you can often feel little "pulses" in power between 2000-3000 RPM. Every time that happens, you're throwing away power/MPG.

87 octane does contain slightly *more* power per unit than higher octanes, BUT it has less knock resistance. For engines such as your Cavalier that do not benefit from higher octane by increasing timing advance, they will get the best MPG on 87 since they able to use the engine's full potential on that gas.

93 octane doesn't give you more power persay, but it lets higher-performance engines run closer to their maximum potential by not pre-igniting.