GenVibe - Community for Pontiac Vibe Enthusiasts

Ok, it is official. I get lower gas mileage in my 04' base vibe when I run premium gas. To the tune of 2-6 mpg! I have tried several different brands. Hmmm, no Shell though. If I run premium on the same road conditions and same driver, I get lower gas mileage. I do not notice any driving differences between premium and elcheapo. Also the midgrade gas (89~91 octane) does not do this-IE same MPG's as lower grade (87~89).Anyone else see this?

i think it takes the ecu a little while to adjust to the diffrent octane

I noticed one heck of a difference when I switched to plus. A minimun 3-4 extra mpg if not more.

You may can get better mpg with premium but does it worth the exta money???Plus running with premium only in you base engine built to run with 87 octane will accumulate crap from the non-burned octane.It help cleaning the engine running highter octane one in a while (every 3000 miles or so).

Quote, originally posted by Sub-Vibe-R »It help cleaning the engine running highter octane one in a while (every 300 miles or so). isn't 300 miles that every tankful? in my car, mileage did improve after I reset the ECU, undo the ground , push the brake pedals few times to completely drain the charge. wait an hour, and reconnect.

To me it is worth the money. I don't have to take extra time to fill my tank as often and the Vibe seems to run better on it.

Quote, originally posted by bellwilliam »isn't 300 miles that every tankful? in my car, mileage did improve after I reset the ECU, undo the ground , push the brake pedals few times to completely drain the charge. wait an hour, and reconnect.Sorry, I forgot a 0. I meant every 3000 miles or so. I do put 92 octane in my Vibe after every oil change.

Quote, originally posted by Sub-Vibe-R »Plus running with premium only in you base engine built to run with 87 octane will accumulate crap from the non-burned octane.Unburnt octane?!?! Octane isn't something that is burned or left unburned. Octane is a rating, a number measuring how well the fuel resists detonation.

Just a stupid question here but if... Quote, originally posted by Sub-Vibe-R » Plus running with premium only in you base engine built to run with 87 octane will accumulate crap from the non-burned octane. Then why... Quote, originally posted by Sub-Vibe-R »It help cleaning the engine running highter octane one in a while (every 3000 miles or so). Would think the crap would still be there, right? Just kinda teasin, sorta... Anywho... If someone gets 3-4 mpg more and that's about 10% higher than normal then if the price of Premium is 10% or less more than regular then it's really at no extra cost. Some people notice a slight improvement in using a higher octane. If that slight improvement is worth the extra cost to someone then it's all cool, right?For me, when I had my Ranger, I would put in mid-grade because most reg grade gas caused a knock and a noticable lack of oomph in pick-up (no pun intended) and it seemed that I would get better mileage (1-2 mpg or so). I usually just paid 2-3 cents more for the higher octane. It was all good. Same with my Vibe GT now. I don't mind the Premium gas price over the Reg octane I would have needed for a Base because I generally only pay 12 cents more for Premium than Reg. 12 cents for 40-50 more horsies and a 31-32 mpg average isn't all that bad, aye?Dave

I ran one tank of 93 through my base vibe and got worse mileage, but I didn't reset the ECU. Since I've been getting 36 mpgs on 87, I'm happy. I would need to push 40 average to be breaking even on the extra cost,, but I don't think i can expect that to happen

Resetting the ECU should be unneaded since the air flow doesn't change and the A/F ratio will stay the same regardless of octane. In a base, you can actually get worse performance from 93 octane. Its resistance to knock actually gives it a less volitile ignition in a lower compression motor. 89 octane is probably best in a base that gets full throttle, especially at lower rpm. Using the lowest octane that will allow the motor full advance without knock is optimum for all aspects of performance.

I ran at least 3-4 tanks of each and compared. Strangely I really do not notice a performance difference in our Vibe from premium to cheapo. My Chevy Silverado there is a HUGE difference. Kinda comparing apples to oranges, but I think I should of noticed at least a little something. I was thinking about the ping/knockecu/timing connection. It seems to make the best sense to me.