View Full Version : Your Mileage May Vary...

09/12/2007, 07:25 PM
So there have been many threads discussing gas mileage on this site over the years, and a lot of different owners have claimed getting a wide range of average mileage out of their VX's (like anywhere between 12 and 20 mpg). Much of the variation in observed fuel economy is doubtlessly due to different driving styles, tire/wheel combos, and the extensive array of vehicle modifications, not to mention some not-quite-orthodox ways of calculating gas mileage.

I would like to add one more very important variable to the mix of fuel economy factors... the fuel itself. Gas is not gas is not gas, as it turns out. There are a lot of varieties of the stuff, and what kind you put into your VX will determine what mileage you get out of it. I'm not talkin' Shell vs. Mobil vs. BP here - I'm talking about the guv'mint's grades of gas. Your state and/or local government may be having just as influence on your average mileage as your right foot.

I recently had a eureka moment when I had to drive the VX from upstate New York (Catskills region) to Rhode Island for a work meeting (in the middle of my freakin' vacation!! :mad: ). I live in CT, so I am stuck a 10% ethanol oxygenated blend. I had half a tank of the stuff in the VX, so I had to top off. I recently learned that Ulster county, NY (where I was vacationing) had conventional gas, so I made a point to top off there. 9.76 gallons went in, pretty much exactly half of the amount I usually put in. On that half tank, I got my usual 15 +/- 0.5 mpg (all highway, ~80-85 mph). I drove to Rhode Island for my meeting, driving just as fast as always (maybe faster with no traffic), and stopped on the way back to fill up. I calculated my mileage as always, and it came out to 16.6 mpg! With only half a tank of conventional non-oxygenated gas mixed in with the 10% ethanol crap! By extrapolation, I probably would have gotten around 18 mpg if it had been pure conventional gas! WTF?!? I was shocked. I have seen these kinds of big changes in mileage every now and then, but I never knew why. Now I know it's because the conventional gas I buy in VT on ski weekends or in upstate NY during summer get-aways gives me better range and fuel economy than the crap I have to buy in CT.

My state gov makes me give up 3 mpg for cleaner emissions - while making me buy more gas, pay more in gas taxes, and while increasing gas consumption state-wide, while the country struggles to reduce it!!

Many, this burns me up (pun intended) on so many levels I don't know where to start being mad! I think I have found a cause to champion...

Check this map (http://www.mobil.com/USA-English/GFM/Files/US_Gasoline_Map.pdf) for geographic specifics. Similar information is available at Exxon's website as well. Bottom line... if you live in (or buy gas in) one of the areas that require "oxygenated" gas blends, you are losing 2-3 mpg in your VX.

For more reading on gas, reformulated gas blends, octane, etc., see Wikipedia's entry (http://en.wikipedia.org/wiki/Gasoline) as well as any of the gas company's websites.

09/13/2007, 02:49 AM
Atlanta uses the "special fuel blend" during the warm months and I've also noticed worsening economy - didn't think much of it because I know it contributed. Now that I've gone SC and have to use Premium, it'll be interesting to see what the differences are - I started keeping track once again.

-- John

09/13/2007, 04:47 AM
According to a recent study a gallon of gas is also not a gallon. Gasoline is a liquid and expands and contracts with the heat. When the station buys gas it buys a gallon based on a set temperture. This means they alwasys get a gallon. However, when you pump you get a gallon based on the temperature at that given time. Best results are when it is cooler. So buy in the AM because even though it gets cooler in the evening the gas is still probably expanded. They did not measure whether you get increased performance with the gas when it is expanded or contracted or that might be the same thing

09/13/2007, 07:49 AM
Well, its obvious that we need cleaner emissions. BUT, if that causes us to use more gas, than what is the point? Its like light cigarettes, if you don't get enough nic from a light cigarette, you're just going to smoke more, so what's the point?

:confused: Bart

09/13/2007, 05:28 PM
I would like to see the math of the trade-off between burning more gas and emitting less due to oxygenation. It is hardly beyond government to do something stupid, you know. Whoever proposed oxygenated gas could easily have shown that emissions are reduced 5% per gallon of gas burned, without factoring in the increased gas consumption per mile driven, and ending up with a policy that burns more gas and produces more emissions per 1000 miles driven.

For example, let's say oxygenation reduces emissions by 10% per gallon burned. Hmm... well, hell, I'd vote for that!

But let's say you get that reduction in emissions at the cost of decreasing gas mileage by about 16% (like my observed reduction from 18 mpg to 15 mpg). For a thousand miles driven, I'd burn 66.66 gal of oxygenated gas instead of 55.55 gallons of conventional gas. Just multiplying those numbers by 90 and 100 "emissions units" (respectively), I am putting out 5994 "units" of emissions instead of 5555 "units" per 1000 miles running on the "cleaner" gas! That would be bad for me, bad for the environment, but (how did we just know it was going to work out this way) better for the state government that is now collecting 20% more in gas taxes from me!!

Of course, this is not necessarily the case - I'm making huge hypothetical assumptions here to illustrate how a mistake can be made in enacting oxygenated fuel requirements, and how the promise of fiscal enrichment can make legislators look the other way when good sense stares them in the face.

Like I said - I want to see the math.

09/14/2007, 02:19 PM
Have you ever tried Lucas gas treatment? I have no idea what's in it but it really boosts your mileage. My wife and I routinely see 40-50 more miles per tank full. It costs $8.99 and it treats 10 tank fulls, At $3.00 per gallon the stuff really pays for itself. If you try it let me know...and no I don't work for Lucas.