What's the best gas to use? 87, 89, or 91?

[Jaycie685]

I own a 2004 base Vibe and was wondering if using a higher octane gas gives your car better gas mileage? I just put regular 87 from Shell and I seem to be getting really crappy gas mileage. I do both freeway and city driving every day. I seem to average almost 300 miles on a full tank. What do your cars average? I think the actual gas mileage is less than the advertised "29 city, 34 highway"

[Mr. Poopypants]

Welcome to GenVibe. If you use the search function, you will find a few hundred posts on this topic.

[Raven]

Just ask Ragingfish.

[RIT]

The Btu content (amount of energy) in gasoline is the same for all octanes of gas. So, if you are using at least the minimum recommended octane for your car, such that the timing does not have to be reset by a knock sensor, then there is no explainable reason, despite what many people will tell you, why you should get better gas mileage by using a higher octane. You are wasting your money - from a gas mileage viewpoint.

[GMJAP]

Quote, originally posted by Jaycie685 »I own a 2004 base Vibe and was wondering if using a higher octane gas gives your car better gas mileage? I just put regular 87 from Shell and I seem to be getting really crappy gas mileage. I do both freeway and city driving every day. I seem to average almost 300 miles on a full tank. What do your cars average? I think the actual gas mileage is less than the advertised "29 city, 34 highway"As others said, there are many topics on this, though most relate to using Premium in the GT. Essentially, any mileage gains you get by using higher octane in a Base aren't enough to offset the higher cost.I get 33-35mpg consistently; a family member with an auto gets about 30mpg

[joatmon]

I just ran a search for "mileage" and there really are a lot of threads about it. a good one that has been active recently is Actual Gas Mileage people posting what mileage they have been gettingsome people say that using 89 or 91 octane in the base will help gas mileage, but it didn't for me. I tried one tank, and my gas mileage dropped for that tank, but that could have been caused by many things, such as:- my harder acceleration to see if the higher octane gave me any noticeable power improvements (it didn't)- the random variance in how full is full. Sometimes I can squeeze in a fair amount of extra gas after it seems like the pump is telling me it's already full.- the car's computer has a learning aspect to it, and it may take multiple tanks for it to make some adjustment to deal with the higher octane.

[GMJAP]

[QUOTE=Jaycie685]I seem to average almost 300 miles on a full tank. QUOTE]PS- if you're just seeing about 300 miles when the gas gauge light comes on, then you're probably getting decent mileage. My light comes on around 10 to 10.5 gallons used (3 to 3.5 left). This would put you around 29mpg.

[ragingfish]

Quote, originally posted by Sunny »Just ask Ragingfish. ***grrrrrrrrrumble***

[kcinmi]

Just this past weekend I burned up an entire tank of gas, It usually takes me about 3 or 4 weeks to go thru a tank, but wanted to see what kind of mileage my car was getting at 7000 miles on the odometer. At a consistent speed of 80, and 348 miles, my refill was 10.4 gallons. Equates to a little less than 34 miles to the gallon. I can live with that. 2004, base, auto, drivers window and sunroof open. Ive actually noticed a mileage drop if I use a higher octane gas, not to mention you dont need it.