Here’s a reference thread for all of you lucky ones that get 400+ miles per tank... there are many other threads just like this one... on this thread (attached) it looks like DaveB is the only lucky one that the extraordinary mileage…

https://g35driver.com/forums/g-spot/169790-gas-mileage.html

 

Lots of people seeing 24+mpg and 400+ miles in this thread

https://g35driver.com/forums/showthr...ht=gas+mileage

 

by far in the minority... a quick perusal and I counted 10... however dozens reported far lower... of the 10 many stated "best" was 24+ or 400+... very few (possibly none) said it was on a regular basis... however many, many reported much, much lower... Thanks for confirming that most threads and posts out here (other this one) report far lower than your remarkable mpg and per tank.

Keep searching though... maybe you'll find another thread where the far minority shows these superb mpg... It makes it easy when you confirm it for me…

 

I'm lucky if I get 300 miles per tank regardless of the octane.

 

So about 15% of the respondants in that thread must be lying What exactly are you trying to prove by debating this now? The fact is others on this site have seen the same MPGs as myself. Are we in the minority? Yep, but that doesn't change the fact that it's the truth. As they always say, "your results may vary".

 

Since gas stations around here recently started charging a 15 cents premium for mid-grade/hi-grade instead of 10 cents I re-ran my numbers based on my previous mpg testing (not very scientific testing though). What I came up with was that anytime regular was over 2.70/gal it is more economical to use mid-grade since I got consistantly better mileage. This was up from around 2.50 originally. Needless to say, I haven't even considered using regular grade since I did the initial testing right after Katrina hit two years ago.

 

I have not read this thread so don't flame if I cover something that has been said.

I would run 91/93 in the hot months and 87 in the cold. (if you don't push your car that hard)

 

I have a 06 AT Sedan. I run it with the castrol syntec European 0W-30 w/ 93 octane (with out ethanol, for those in states with it.)

I drive 90% highway it seems, and in nice weather, like 60-80's I can get over 400/tank. I usually set the cruise between 75-80. And I do hit it hard almost daily on the highway...gotta mess with people.

 

Ok , easy on the guy, I get 400-440(depending how much I feellike stretching it) in my 06 x. I have done all of the experiments with octanes and mileages and cost analysis, but right now in Maine there is a 30 cent diff./gal. from regular to super(92). Truthfully, the car has alot more snap on the high octane, but I think I am an abnormal user in that I will frequently burn a tank of gas in one day all on the highway, there is absolutely no benefit to wasting an extra $6/tank to set my cruise @ 80mph. I know some will talk about deposit build up etc, but I travel around 45-50k per year, I keep cars 4-5 years and have nevr had a "build up issue", my last car went 300k and had a ton of life left. I do every couple of months run a bottle of techron through the car. My point is depending on what your need is for the day in a sedan you do not have to run premium. my average mpg is 23.5 @ 80mph with the occasion 10 miles stretch at well slightly higher speeds if you know what I mean.

 

You don't have anything to worry about regarding deposits. 87 octane has the same detergents as the higher octanes. For highway driving, I think you'll be fine with 87 or 89. Only under high load/high rpms will the engine potentially experience severe detonation. At a steady 2500-3000rpm cruise, you'll be fine.

BTW, nearly 24mpg with an X is really good.

 

I know your an engineer or at least very mechanically inclined.But please explain this reasoning further.I.m curious as to the effects of outside temp. on different octanes.I personally run 94 almost exclusively,am I wasting my money?

 

Octane is a fuel's resistance to igniting. The higher the octane, the more resistant it is to burn.

The VQ35 has a relatively high compression ratio (10.2:1) which is good for performance, but it also requires the need for higher octane fuels because higher compression ratios generates more cylinder pressure and heat. Basically, the higher octane is general safeguard and can resist preigniting before the spark is lit.

In hot weather, the air is hot and less dense with oxygen and engines run much hotter. The engine is heat soaked and constantly heating the incoming air above ambient. The higher octane helps reduce the chance of the detonation.

In cold weather, the exact opposite happens. The engine is running much colder as is the incoming air. It is quite possible that in temps below 60 degrees or so, you can get similar engine performance and efficiency by running 89 or even 87 octane air.

Clear as mud?

 

DaveB, I agree 24 pmg is great, for this kind of performance. From 0-24K I got around 21-22 consistantly, I think my tread is worn is may be allowing the increase in mileage. To my surprise when purchasing the last st o sneakers on my last car the review @ tire rack stated people lost 2-3 MPG from the aggressive design, I thoughtthat was a joke until I installed them and lost the same 3 MPG. Which brings me to an interesting question of what to replace the OEM's with this fall.......

 

I've run 384 miles with a 17 gal fillup, so 400 miles is easily attainable. I've kept mileage records on my 04.5 since new and I'm averaging 20.6 mpg for the life of the car, mostly city driving (by the wife of course). I run 89 octane exclusively.

 

its not just about mileage ..its also about a cleaner engine ..

more so a cleaner engine ..

i run only 93 octane