$ The Nation Fuel Cost, and VX MPG Record Thread. $

[VX KAT]

I've been keeping track of my MPG for years and years...I mean like 20+ years....don't know why, just keep doing it...put me in the neurotic category I guess... I don't do it to change my driving habits to max MPG, or anything like that...I just keep recording it cuz I'm curious.

I got 21 or 22 twice, all stock, all highway driving (actually it was driving to Moab 2009 and then driving to New Mexico to meet up with some other Moab-bound VXer, and then drive up to Moab.

Seriously, I do remember there was a tremendous (I mean MEAN) tail wind on the NM trip...it just HAD to have an affect, cuz I had skids, roof rack, f/s spare in basket...and of course I did factor in the adjustment for my larger tires.

So I know it's "possible" but extremely unlikely to hit the 20s for anything but a stocker w/o sticky rubber. I also believe the summer/winter gas formulation has a tremendous impact on it (in places where that exists). When I lived in LA the winter gas (pretty sure it was the winter formula) dropped my MPG by at least 10%...booo!!! So maybe some of that issue is affecting MPG on some VXers?

Some here mentioned they had some increase in MPG when they used Premium all the time.....so I tried that for a while...like 13 months!....didn't see much difference and went back to regular.

[twalker920]

Some here mentioned they had some increase in MPG when they used Premium all the time.....so I tried that for a while...like 13 months!....didn't see much difference and went back to regular.

Premium has VERY little to do with efficiency or power. Anyone interested should read this article from a recent issue of Road & Track:

http://www.roadandtrack.com/auto-new...m-fuel-futures

I am especially glad he says "In fact, depending on its blending, a premium fuel may actually contain less energy per unit volume than regular."

More Octane does not equal more power. Use the mfg's recommended grade. That's all. The only other significant difference is how much non-gasoline is in your premium gas. More super detergents in the premium fuels actually means less real gas per gallon...

I put regular in my VX and Triumph bike, as recommended by Triumph.

The only exception to this is one gas station near me that sells premium with ZERO ethanol during the summer (as opposed to 10% at all other stations). That can make a difference in power and efficiency since ethanol has a lower energy content than normal gasoline. But it's spendy stuff - usually 30 cents higher than I pay for regular. I have only ever put it in my bike and gotten an extra 40 miles out of a tank (before the light came on - I kept waiting, and waiting, and riding really slowly).

[VX KAT]

thanks tw....great info!

Dang, can't find the thread about Premium yielding greater MPG...I recall somebody had done a pretty long term test and was posting the results that supported it.
But.......... along the way I decided to capture many MPG/Premium fuel threads and discussions to put in my reference file.


Here's the MPG/Premium references I grouped:


Octane and premium discussion from 2009:
http://www.vehicross.info/forums/sho...ht=mpg+premium


MPG / AWD/ locking hubs/manual hubs from 2009
http://www.vehicross.info/forums/sho...ht=mpg+premium


MPG / Premium discussion from 2008:
http://www.vehicross.info/forums/sho...ht=mpg+premium
http://www.vehicross.info/forums/sho...&postcount=104


MPG and altitude, from 2008:
http://www.vehicross.info/forums/sho...&postcount=107


Can MPG be increased, Rolling resistance, tire size , PSI, from 2007:
http://www.vehicross.info/forums/sho...ht=mpg+premium


Actual MPG obtained - discussion on what mods affect it, from 2007:
http://www.vehicross.info/forums/sho...ht=mpg+premium


Here's an older thread discussing MPG from many original owners, or very early owners, from 2005.
http://www.vehicross.info/forums/sho...ats+VX+mileage


Octane- older discussion & POLL from 2004
http://www.vehicross.info/forums/sho...ht=mpg+premium


Any tips for increasing MPG, from 2004:
http://www.vehicross.info/forums/sho...ht=mpg+premium



FUELLY
Website where you track your MPG:
www.fuelly.com


GASBUDDY.COM
Helps find lowest price gasoline in area
Nationwide maps, tips,.
http://gasbuddy.com/

[89Vette]

Dang, can't find the thread about Premium yielding greater MPG...I recall somebody had done a pretty long term test and was posting the results that supported it.

I've read several of the threads you linked above. I don't know which link it is, but there is a long-running thread about which octane do you use. In it, I'm fairly certain the conclusion was that lower octane normally created better power.

Because higher octane fuels contain additives that "retard" detonation, they also slow the flame-front. In real terms, that's the speed of combustion. FWIW, the best [cylinder] chambers are the ones where the fuel is squeezed into the smallest ball -- so the detonation creates the fastest flame-front.

One of the posters in the octance thread talked about using 85-octance -- which most of us haven't ever seen. For similar reasons in my paragraph above, it was shown that lower octane created better power -- because it burns faster.

With high-compression engines you don't want the detonation (created by the higher cylinder pressures), so the fuel has to be "de-tuned" to avoid pre-mature explosion. The end result is you still can make more power with high-compression and high-octane, but you also should use the lowest octane necessary to avoid detonation. It provides the best power/efficiency and the lowest fuel cost.

100% gasoline (that's still available in a few 91-octane stations) will improve MPG. But I'm doubtful it raises MPG's enough to offset the extra cost/gallon. (Gasoline has more BTUs (power) than ethanol -- which is why it provides better mpg. I believe it's only in the 3-5% range [more powerful] but the cost can be more than 3-5% higher.)

[twalker920]

FYI 85 octane is our "regular" at Denver altitudes, 87 is mid grade and 89 premium. There are a few places around town that sell 91, but you just don't need it. At this altitude again with the engine getting less O2 per CF it is like reducing your cylinder compression, which inherently reduces the chance of knock...which is all higher octane is for.

Ethanol-free gasoline is best used if you are going for total range on a tank. It will get you further than the emissions-friendly diluted stuff. It's one of the reasons I chose to use it in my bike so I could go maybe 150+ miles up in the mountains without refueling (gas is 30-50 cents higher in most mountain towns - some due to tourism, some to actual transportation costs to remote areas). So if I can go further on "cheap" lowland gas, it's worth it to me sometimes.

Flex fuel vehicles that can run on gas or E85 (worst marketing decision ever) can see as much as a 20-25% range (it might even be more - I am recalling another Road & Track article) hit by using a full tank of E85 over gasoline. That's a big deal if you're a rancher or oil/gas-field worker out in the middle of nowhere for extended periods of time.

At least we don't have any complicated factors to consider when buying gas!(removes tongue from cheek)