daryll40

I've only completed 1 tank full of regular gas, but here is the preliminary results of my experiment:

As most of you know, I mix 50% 87 octane and 50% 93 octane to get a combined 90ish octane. I tend to tilt the mix to bump it slightly above 90. Using that mix I have consistently gotten about 17 to 17.2 MPG around the hills of Pittsburgh. Almost exactly the same as I got with my old 2004 LS430. This mileage was no better than when filling with full 93 octane.

I decided to take the experiment to the next level. I ran the car down to fumes then filled it with 87 octane. Yeah yeah I know all that crap about driving a $70,000 car and chintzing on gas. Chintzing is HOW I accumulated the wealth to support a $70,000 car lifestyle, etc.

Anyway, after 1 tank it appears that my MPGs dropped from 17.1MPG to 14.6MPG. Just under a 15% reduction in economy. The car doesn't seem to ride any different although I suspect after a NUMBER of tanks of 87 octane I might see some difference.

Anyway, around here (today...changes almost daily as we all know), 87 octane gas is $3.65 while 93 octane gas is $3.89 or about 9% more.

So the bottom line is that it APPEARS that 90ish octane is the peak of the yield curve for your gasoline dollar. Going to all "regular" gas actually costs more than mixing 93 and 87. And using 93 all the time is wasting a few percent (some might argue that it's too small an amount to worry about).

acecert

Be thankful, we're about $4.09 out here in CA for 93. :-)

daryll40

Hard to be "thankful" for "mere" $3.89 gasoline!

rominl

iTrader: (4)

lol, dave, we don't even have 93 here, it's all 91

thank god a lot of places in OC are still below 4 :0

alsilverbullet

In S. Florida 93 octane is averaging about $3.94. I figure by the end of the month we will be paying $4.00

daryll40

I'd guess by the end of TODAY you'll see that 6 cent increase!

clemgrad85

What you might also try is a credit card that gives discounts for gas. I am one of the evil poeple that supports Exxon (please, don't burn my house down), but I put my gas on my Exxon card and get a 3% discount. I use the premium gas and that generally gets me down to the mid level gas price. I have heard other cards give back more credit than that.

daryll40

Actually, here in Pittsburgh the Giant Eagle Supermarket company has an even better deal that links all purchases (groceries and gasoline) to gas discounts. But your point is good. A REAL "value seeker" will do BOTH (buy gas with the best discount cards AND squeeze the optimum miles per octane!). Again, "seeking value" is how many, like me, get to the Lexus in the first place.

Nospinzone

Daryl, that drop in mileage with the 87 gas seems too drastic. My guess is a combination of different driving and imprecise gas measurement are to blame. Try a few more tanks of 87, I suspect that that your measured mileage will improve to almost your 93 octane mileage.

daryll40

It's very possible. I'll keep watching this and reporting in as I get numbers.

Craig B

I put the best fuel in that I can BP 93. I wouldn't put in anything less. What ever you decide, it's your car and your money. I average 21-22 MPG in the city now that it's warmed up here. In the winter, it was around 19-20 MPG
with BP 93 octane.

Craig

4TehNguyen

iTrader: (1)

random post: this similar to buying 70/30 lean ground beef vs 90/10 lean ground beef. I got bored one day and did calculations and you get more effective meat/dollar in the 90/10 lean

daryll40

"I average 21-22 MPG in the city now that it's warmed up here."

"here" has to be some VERY flat place with a moderate climate.

vanlex

Crunching some numbers here, I just filled up on 92 octane for an effective $5.42 USD per gallon.

daryll40

Where do you live?