R.G.: What in God's name did you do to your rotary to get 27 mpg from it at any speed? Tell you what, tell me what you did and I'll cut you in for 10% when I market it......

Tell me and I'll cut you in for 75%!!! I'd just be happy to be able to get that myself.

Let's say the average fill up is 13 gallons every 230 miles (17.7mpg). (meaning you dont run it till it's empty).

2.00 a gallon for 87

2.20 a gallon for 91 (or 93)

We'll take the average person's mileage of 12k a year. That's 52.2 fill ups a year.

The cost of a fillup of 13 gallons at 2.00 is 26 dollars.

The cost of a fillup of 13 gallons at 2.20 is 28.60 (wow $2.60 savings a fillup!!)

$2.60 x 52.2 fillups a year = $135.72 a year in gas savings. Most of the people here that's one day of work a year, or maybe even half day, or an hour. Is it really worth it?

Even if gas prices skyrocket assuming that the difference between premium, and regular is always going to be $.20 then your savings on a 13 gallon fill up will always be 2.60. Cmon people. Play it safe, give the car what mazda and the gillions of dollars R&D $$$ ask you to give it...

My $.02

Not my car. It sputters and spits and frowns at me like a puppy hit with a rolled up newspaper.

there are plenty of people on here , including myself, that have had 24 mpg or better driving between 70 and 80 mph. drop the speed on the same route to 55-65 and your there

they more than that for coffee or bottled water

Then something's wrong with your car. Mazda clearly states in the manual that regular gas CAN be used, although reduced performance may result. Now for me, reduced performance is not equal to sputtering and spitting.
But if premium solves this problem for you, by all means, run only premium. I'm fine with regular.

oh i think it was gear selection math or or bad numbers(i.e trip odo reset by accident or used b instead of a etc)

ive changed my mind on the octane debate recently after som estudy and questioning of folks with more knowledge than me here is what i said and now believe

if you have an auto 8 i would never run anything but premium.

just for the fun of it when i filled up today i checked my milage, and it was 13.5 miles per gallon! YEAH BABY!
i do almost no freeway driving, and am at full throttle about 50% of the time!

Can we keep this quote and add it the ad when you try to sell the car?

Brillo got that number on the freeway by holding it around 70 mph. Gas mileage is hugely affected by just 10 more mph cruising speed. I've personally gotten 29 mpg freeway in a rotary before but it wasn't a Renesis.

There is a rather sudden switch over at 4200 RPM or slightly higher at cruise load where the A/F target goes from 14.7:1 to 12.9:1. This will adversely affect your mileage.

Trying to get MPG from an 84-mile trip is totally futile. The margin of error there is at least plus or minus 3mpg. Even a small difference between pump shut-offs makes a huge different in MPG in short-trips.

For example --
You went 84miles at 22mpg -- so that's about 4 gallons of gas.

Well what if the pump shut off early and to get to the fuel level that you started out you'd actually have to put in 5 gallons -- well now you only figure that you got 18mpg.

Combine that with different temperatures and the fact that wind was probably at your back going back home and you see where all that "increase" in MPG came from.

Basically, I bet if you had ran that tank dry and then filled up at the same pump that you filled up before leaving Austin you'd probably find that your MPG was little different than normal.

I've gotten 27 mpg on my 3rd gen when it was stock cruising at 65mph for a full tank without stops (nearly 500 miles before I stopped to fill up, 20 gal tank). I probably had a tail wind because in that area the wind usually blows in that direction though...

I consistently get 22mpg cruising at 75mph but it's no longer stock ;)

I got 13mpg in autocross and 8 mpg when I tracked it at the Revolution :D

i run 87 all the time

I ran 87 octane all last year and this spring. It ran okay but I felt as the fuel level got closer to empty the car just got sluggish. This week I put in a tank of 89 and noticed an reasonable increase in performance. And the car never felt sluggish. Maybe its harder for people with the auto to feel the difference, but in the manual it is definitely more apparent. The only downside is the price, I paid almost $30 bucks to fill up at $2.25 a gallon! I still got around 18 mpg which is my usual. I think next time I'm going to try Sunoco b/c their mid grade gas is 91 octane. And on a side note, I almost got 20 mpg last week. I think the key is to not downshift on the highway.

note - i am not saying use premium in the auto's for increased mpg. i am saying to use it to help prevent carbon lock that we are seeing on quite a few auto 8s

That probably won't do it. Even though the detergent package is usually better in "premium", it really isn't effective enough to be a "shock treatment" to the upper motor like a legitmate solvent.

because it burns more completly there is less chance of carbon build up in the first place

Cmon people, look at the math presented to you. By one less carmel maciado from starbucks a week and there will no point in not putting in 91+ or better yet, there will be no point for waiting 20 minutes in line at a shitty gas station to save a nickel on a gallon of gasoline...

Funny story... by my house here in san jose, there are two gas stations kitty corner to each other. One is an Arco, one is a Shell station. There is a difference per gallon on average of $.10- $.12 between the shell station and the arco (arco being the cheaper). Everytime i go to fill up (especially on the weekends) the arco station has people EVERYWHERE waiting in line forever and ever to save their 10 cents. The shell station always has a spot for me, my time is worht more then the buck fifty i would save by going to arco.

If people take the time to do the math my shell station would be more crowded, so i say, stay ignorant people, dont crowd the smart people's gas stations!

Nah, it doesn't. If anything, lower octane will burn more "completely" because it starts to combust earlier.
The only thing that will realistically change the carbon situation (other than a change in driving habits) is a more agressive detergent package.

thats what i thought to jeff and what i have said many times before on this forum. but then when mazda suggested to some of the AT owners to run higher octane i was confused. so i did some research on my own and did some asking around.

the conclusion was- ignition of the lower octane fuel can happen so quickly that the spark and flame front may not ignite all of the gas. leaving more unburned and leading to more carbon deposits. higher octane fuel burns slower allowing for more complete/clean combustion so makes less unburned carbon to build up.

I have an automatic and use 93 octane. I used 89 for a while, but notice the car runs better and I get better gas mileage with 93. To me it is worth the cost. No scientific study, but I also get better gas mileage at 80 mph, than 60 to 70 mph. My experience is based on the 560 mile round trip from Knoxville TN to Greensboro NC which I drive quite often, which is over the Blue Ridge Mountains both ways. I get around 25 mpg on that trip, and average 19 to 20 mpg around town driving back and forth to work. Sometimes I do get a weird tank where i get only 17 mpg, I believe that could be from variance in gas quality to my unnormal driving habits. Overall I've gotten about 22 mpg since I've had the "8" in 16000 plus miles.

Someone is going to have to show me exactly how that is possible before I would accept that explanation.
What could possible stop the flame front? The change of the combustion chamber shape?
http://www.mazdamaniac.com/images/smiles/icon_bs.gif

sorry flame front was my wording could cause confusion.. ill look up the info again and provide some links later.