This is NOT by any stretch a scientific test. But with the price of gas going way up I figured I'd give it a try.
Regular gas/89 octane = 24mpg say at $1.59/gal = $0.06625/mile
Premuim gas/93 octane = 26mpg say at $1.79/gal = $0.06884/mile
So yes, the regular is cheaper BUT for $0.003/mile I'll use the good juice. Just thought I'd pass this on.
Damn, the Max is almost as fun to drive as my Z and it gets better gas mileage. I said ALMOST!

 

You do realize that after driving the car on 89 octane the car needed to adjust to 93 octane making your results a bit off...

 

Which way off? Better mileage on 93?

 

26??? 24 even, jesus, I never get near that, I get 21 on normal tanks and 23 when it's mostly highway. My Tbird did as well or better with a 4.6L engine

 

It's mostly highway driving (100 miles/ day), no jackrabbit starts and an occasional 100mph passing some slow sob.

 

Just a word of caution for you guys running any gas lower than premium in our Max's. Yeah, when gas was high, I paid the price when I started running 89 Octane in my '95 for a while. Well, I ended up with ruining two O2 sensors. The car also had a hard time starting, unless I stepped on the gas to help it (sometimes I even ended up flooding the engine from this, too). Then, eventually, this on-going process also ruined my starter as well. Man, was I frustrated. I didn't find out what was wrong until it was already too late.

 

Better mileage on 93. Here's how it should be done:

Run 2-4 tanks of 89 and use the next 4 tanks for this experiment. Run 2-4 tanks on 93, for car to get used to it, and then use the next 4 tanks for the experiment. I bet you that the 89 octane numbers would be down a bit and the 93 octane numbers would be up a bit. Great thing you did anyway...

 

I notice there's a tendency to deal with things in an absolute sense on the forum. Well, 20 cents more when fuel is 1.639 = 12.2% more for super. A blue moon ago when regular unleaded was 1.099, super was, well, you guessed it, 1.299, or 18.2% more expensive. So super is relatively cheaper today than in 1999, but absolutely more expensive.

By now, doesn't everybody know the "$16.67" per $1000 financed rule? I mean heck, GM has beaten that into our heads for a couple of years now. That's 0% for 60 months. How much do you want to borrow at that rate? Me, $0.00. Reality is at $20,000 down, a Touareg is over $800 per month for 3 years. Not easy to afford. Makes me wonder sometimes how everyone seems to have a 30,000+ car these days. Must have a nice job or a lease imho!

 

None of those problems could have been caused by the wrong grade fo fuel.

 

They call that a placebo effect.

 

*lol* at the firm we call it non-sequitir, that, or IQ = 89.

If I'm not mistaken the new Maxima REQUIRES super unleaded. The 4th gen RECOMMENDS super unleaded.

My aunt uses regular unleaded in her 2k2 M3. The motor blew at just over 6k miles leaving oil all over the roadway. The placebo man would probably say the wrong fuel (obviously the E36 and E46 REQUIRE super unleaded) caused the motor to blow too, but there is a known issue in early 2k2 production M3's needing motor replacement. If BMW ran their shop like Nissan does, those M3 owners would probably have to pay 17 grand out-of-pocket for new (remanuf.) motors because the Nissan way is "it's not covered under warranty."

 

Is BMW still having engine problems with M motors? I thought they'd iron that out by now.

 

The 2k2/3 do not require premium. As per my owner's manual, minimum octance required is 87, but 91 is recommended for maximum performance.

 

Which is exactly the same recommendation as the 4th gen Maximas.

By the way, since when was 89 octane considered "regular?" i thought it was 87 octane. 89 is mid-grade in my neck of the woods.

DW

 

Well, at least Nissan engines don't blow up. I'm sorry but that's damned embarrassing for a premium BMW car like the $60,000 M3 with hi end racing technology to blow it's motor. I bet your Aunt didn't even drive it hard.

DW

 

You think the gas did that?

I feel it to be a coincidence.

 

Yeah, me too. I would'nt think any octane of gas could cause this, but this is what my mechanic told me at the time. He's been servicing Nissans all his life. So, I had no choice to believe him, and I avoided from ever putting anything lower than 91 Octane in our Max's. If Nissan RECOMMENDS 91 or more Octane, then one should stick to this to avoid any possibility of future problems.