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View Full Version : MPG's Dependant on Brand of Gas?



F500
07-22-2011, 08:57 PM
about a year ago, because of the BP oil spill in the Gulf, I got upset with the way BP was handling things and cut up my BP gas card and got a Shell card.

I noticed switching from BP to Shell, my MPG's dropped from 23-24 down to 20-21...NOT good. my gas mileage never did recover.

now that I have the FIAT (I'm still on the 'free' gas from the dealer) I'm wondering if I should go back to BP to get better mileage OR just stay with Shell. Shell IS more convenient for me as there are stations near my home and work, whereas I need to go searching for a BP.

so I guess my question IS: what kind of gas do you use and have you used different brands and noticed a difference in your MPG's from brand to brand? :rolleyes:

SeaDawg
07-22-2011, 09:13 PM
about a year ago, because of the BP oil spill in the Gulf, I got upset with the way BP was handling things and cut up my BP gas card and got a Shell card.

I noticed switching from BP to Shell, my MPG's dropped from 23-24 down to 20-21...NOT good. my gas mileage never did recover.

now that I have the FIAT (I'm still on the 'free' gas from the dealer) I'm wondering if I should go back to BP to get better mileage OR just stay with Shell. Shell IS more convenient for me as there are stations near my home and work, whereas I need to go searching for a BP.

so I guess my question IS: what kind of gas do you use and have you used different brands and noticed a difference in your MPG's from brand to brand? :rolleyes:

My solution to this question would be to run the tank down to very near empty and fill up with BP and see if your mileage improves. Try at least a couple of tanks. If the mileage improves enough in your estimation then switch back to BP. If it doesn't, either run the tank down, refill with Shell or try another different brand and see what results you get. Gas formulations differ depending on what geographical area in which you live. So BP gas in Florida may actually be different than BP gas in Indiana.

Personally, I buy most of my gas from the local Sam's Club which is about 2.3 miles from my house. Their Premium price is anywhere from .08 to .10 or more less than the other name brand gas stations close by. Up until the last month the gas mileage has been great. I think the gas supplier they use may have changed over to the summer gasoline formulation (which means the other stations formulation has probably changed too).

F500
07-23-2011, 12:30 PM
thanks for the feedback 'dawg'. I've used the local Sams Club too because of the prices, but it's not really that close to my house and certainly isn't on the way to and from work, so it's really not convenient. BUT if I'm saving $$ AND can get better MPG's, then I'm game for anything. I plan on doing some 'testing' soon, but after I get about 500 miles on the car and it's considered 'broken in'. then as you suggested, I'll try my Shell for a couple tanks, then off to BP for a couple tanks, etc....and I'll post my results here.

cmj912
07-23-2011, 08:55 PM
I noticed that I was getting over 30MPG city average with name-brand Shell mid-grade (which I thought was good - given the weather and the constant a/c) but that my MPGs have dropped slightly with the last two fill-ups of gasoline sold by the supermarket giant here in the area. Since gas was going up again, I decided to buy 93 from them given that it costs about the same as Shell mid-grade if you use your customer card and they also tack on a slight discount based on points you accrue while grocery shopping.

I haven't done the math but I wonder if it is just the 100 degree temps and the use of the air conditioning or there is a difference in the gas.

italophile
07-24-2011, 12:31 PM
I've never noticed a perceptible difference between [I]brands[I], but the difference between pure gasoline and an ethanol blend is HUGE. Ethanol is less energy-dense than gas, so more of it has to be burned to produce the same amount of energy. In a modern car the mileage difference has been relatively slight (I guess fuel injection systems can compensate somehow), but with my old carbureted cars I saw my mileage drop by about 20% when the local stations went to a 10% ethanol mix. All my carb cars are hard to start hot with ethanol fuel as well.

The only thing I like about ethanol fuel is that water is soluble in it, so any condensation in your tank can't freeze and plug the fuel line in the winter. Ethanol is the main ingredient in fuel line de-icing products like Heet.

This site lists non-ethanol stations across the country: http://www.pure-gas.org/

It is entirely possible that the Shell stations in your area use ethanol in their blend and BP doesn't. Try a non-ethanol station from the list and see if your mileage doesn't improve. I don't have any such stations in my area, but I make a point of feeding my car the good stuff if I travel to a place that does.