Premium vs. Mid-grade

[Clownaholic]

I have been running a little test on our 2004 BMW. I ran two tanks of premium gas and two tanks of mid-grade gas.

The premium gets 28mpg average.
The mid-grade gets 26mpg average.
(under equal driving conditions 30%city/70%highway)

Based on a 15gallon fill up x 2mpg extra = 30 more miles per tank of premium gas.
30 extra miles per tank equals a little more than a gallon of premium gas (current price is $3.25).
The average difference between mid-grade and premium is 10 cents.
Based on that same 15 gallon fill up… the difference between grades is $1.50 per tank

SO, running premium gas in the BMW is more cost effective by $1.75 per tank or…. Based on a fill up every 10days that is approximately 36 fill ups a year or a savings of $63/yr. Which is equal to nearly 1 ½ tanks of free premium gas a year if you run it exclusively vice mid-grade.

[Roger]

nice work! I have a 03 tacoma standard and I have recently started putting in premium because of start-up issues. I filled up a full tank of premium the other day and have yet to notice a drop on the needle. I drive my truck about 40 miles everyday.

[467echo]

All BMW, MB, and other cars that require it is because of the high compression. If you want it to last make sure you use premium!

[CruiseX]

some cars you don't have a choice but to run premo - but your little experiment is interesting. Hopefully I am getting my money worth in my car, but I would not dare downgrade to midgrade to find out

[ocean1]

wow thatsgreat info. thanks Ill try it next fill!!

[DaChrisDude]

Interesting. Would (JJfly's) results be likely to hold true with my '95 Honda Civic? (4cylinder, manual) I don't know anything about how engines work, or what different fuel grades do or don't do...

I've heard different people mention that you can pour different things into the gas and it will give you more HP, better MPG, etc... can anyone share any knowledge on this subject?

[mazilla]

just be weary of engine knock switching between premium and regular. although new cars should have a knock sensor to compensate, but if your gonna commit to premium you should stick with it.

[Jett]

Chris, unless your car is specifically designed to run on premium I doubt you'll see any improvement by going up to it. Higher octane fuels are actully harder to burn than their low octane counterparts. This is so that in a high compression engine the fuel does not burn prematurely. It's called detonation, causes that "knock" sound, and will tear your motor up.

There are a lot of engine additives out there, but since I'm driving a low-compression low-horsepower jeep, I havent tested any. :)

[mazilla]

Chris, unless your car is specifically designed to run on premium I doubt you'll see any improvement by going up to it. Higher octane fuels are actully harder to burn than their low octane counterparts. This is so that in a high compression engine the fuel does not burn prematurely. It's called detonation, causes that "knock" sound, and will tear your motor up.

There are a lot of engine additives out there, but since I'm driving a low-compression low-horsepower jeep, I havent tested any. :)

HIJACK ALERT...


190 bhp @ 8.8:1 compression for the i6 and 147 bhp @ 9.5:1 compression for the 4. what kind of jeep you driving?

[Jett]

I'm driving a 98 GC, with the 4.0 i6. And I've got an 83 cj-7 that gets driven from time to time.

[mazilla]

I'm driving a 98 GC, with the 4.0 i6. And I've got an 83 cj-7 that gets driven from time to time.

sweet, i have a 05 tjl trail rig. is your cj built? do you ever hit the local trails?

[SDFISHMAN]

You guys get better gas mileage then me anyday.. I just found out my 115HP 6 cylinder 2 stroke. 1.3 Mile to gallon.. Maybe 2 miles if i'm lucky and the water is flat

[BigAir]

Justin, only run mid grade in the boat engine, FYI. I did alot of research on that when I had mine up and running. The upper and the lower octanes have crap in them to raise and lower the octane. Most gas is produced as the 89 to begin with, and modified for performance or lack there of.

[SolRo]

Think it's more likely the 2mpg difference was from driving variation than any actual gains.


If you want a 100% guaranteed milage boost, tailgate behind a semi, the closer you do it, the better the results...one car length being about the maximum benefit. It's a combination of lower air resistance and the fact that the big rigs stay at around 60mph when cruising.

The benefit is much more than 2mpg if you do it constantly...i've gotten a 2mpg boost just from doing 3-4 30 mile trips on a tank of gas and the rest driving normaly.

Also, replace air filters (K&N filters do boost milage), make sure your tires are properly inflated, and keep up with oil changes....doing all that will net much better results than buying more expensive gas.

[DaChrisDude]

If you want a 100% guaranteed milage boost, tailgate behind a semi, the closer you do it, the better the results...one car length being about the maximum benefit. It's a combination of lower air resistance and the fact that the big rigs stay at around 60mph when cruising.



Ignoring the fact that you're totally going to piss the truck driver to no end, isn't that illegal?


Think it's more likely the 2mpg difference was from driving variation than any actual gains.

I havn't kept track of my mpg for several months now, but when I was tracking it I didn't see enough consistency to feel comfortable trying out something new. My lil civic would vary from 20-27mpg depending on how, where, and what kind of driving I had been doing. I don't have a consistent-enough driving schedule to accurately monitor it...

I overheard a guy saying you can put denatured alcohol in the gas and that boost performance/mpg?

[acbaldwin]

I overheard a guy saying you can put denatured alcohol in the gas and that boost performance/mpg?
I believe that would put unnecessary wear on the fuel system's components, but yeah, I've heard the same thing.

But then again, I don't give a crap what my mileage is anymore since I live a block from work and just ride my longboard :p .

I get like forty miles to the gallon (of Rockstar:rolleyes: )

[mazilla]

If you want a 100% guaranteed milage boost, tailgate behind a semi, the closer you do it, the better the results...one car length being about the maximum benefit. It's a combination of lower air resistance and the fact that the big rigs stay at around 60mph when cruising.

The benefit is much more than 2mpg if you do it constantly...i've gotten a 2mpg boost just from doing 3-4 30 mile trips on a tank of gas and the rest driving normaly.

Also, replace air filters (K&N filters do boost milage), make sure your tires are properly inflated, and keep up with oil changes....doing all that will net much better results than buying more expensive gas.

somebody watches mythbusters....

[SolRo]

Ignoring the fact that you're totally going to piss the truck driver to no end, isn't that illegal?

well, when you're that close, they probably cant see you anyhow, so nothing to be pissed about.

And technicaly it is illegal, but the fast lane is pretty much the same, only at 90 mph instead of 60...so tailgating behind a semi is probably safer.



I havn't kept track of my mpg for several months now, but when I was tracking it I didn't see enough consistency to feel comfortable trying out something new. My lil civic would vary from 20-27mpg depending on how, where, and what kind of driving I had been doing. I don't have a consistent-enough driving schedule to accurately monitor it...
I've been getting a consistant 22-23mpg for the last year or so

[Dakota]

I ran a test on my cars as well.. and found that premium gives me LESS MPG than regular. . . odd...

[Clownaholic]

My driving habits are easy to track. I travel in off-peak hours, same route, with the cruise control on. Once I get to the city... 1 stop light... 2 stop signs and park.

I'm pretty sure it was the fuel not the driving. But I'll hit Mythbusters with it.

[Jett]

I ran a test on my cars as well.. and found that premium gives me LESS MPG than regular. . . odd...

The octane is higher than your car is designed for, and you aren't getting a complete burn. And consequently not producing as much power for the amount of gas used. Just go with what the MFG. says to.