HeavyDez

Just curious how many mpg everyone is getting. I just bought an '07 SE and I've driven it all different ways on a full tank. City driving gets me 15 mpg driving like an old lady and like 10 mpg driving my way. Expressway gets me
23-24 at speeds between 60 and 80. All speeds are constant so the rpm's are about 2500. I'm pissed off because I feel like I can't drive the car the way it wants to be driven. If I don't worry about gas mileage, the car is awesome to drive. $50.00 a week on gas. What's the deal? Supposed to be 21/28 mpg and that's the average. The 28 highway could be between 25 and 31. I've never seen any number over 24 on my tripometer when on the highway. Will mpg get better when the engine breaks in? Is my ECU regulating the mpg to my driving habits?

xoomer.com

iTrader: (19)

Light you are officially Y3K compliant. Good Job!

BTW is "powered milk" made with diesel?

xoomer.com

iTrader: (19)

Just joking LIGHT. You're the man. I am trying to stock on some sensible food in case of an emergency myself. Guns in NY a NO NO! Food is another story.

As to the gas, there is no need for it. In case of emergency we can't get out of NY, ITS AN ISLAND!

We have 5 hours traffics in the city with a disabled truck during rush hour. I don't think 3 tank fulls will get you out of NY, but good point never the less.

Stay Safe.

jcalabria

Mine was about like yours until it broke in and I also learned a few tricks about the CVT. Now, nearing 10k miles, in all city driving, it will do between 19 & 20 MPG when driven with no regard to fuel conservation. But I have learned that after an initial launch you can feather the throttle back and the CVT will keep accelerating the car even though the engine is only turning 1500 rpm or so. I have driven my 12 mile each way work commute loop to and from downtown Charlotte, including a short 55mph stretch, without exceeding 2000 rpm. The CVT lets you MORE than keep up with traffic this way and returns 26mpg on this route. On the same route, no matter how conservatively I drove it, my '03 Max (3.5L/4AT) never did better than 22. And my Volvo S60 T5 (2.3L Turbo/5AT) does about 22 also, 18 if your heavy on the throttle.

Like you, I was very worried about fuel consumption when the '07 was new, but it has broken in nicely. I am also liking the CVT more and more because of its ready adaptibility to whatever mode the conditions or your mood place it in.

newguyonblock

i ran across a gas station in it was either Va or Nc here that had their pumps rigged

breaks

[QUOTE=jcalabria]Mine was about like yours until it broke in and I also learned a few tricks about the CVT. QUOTE]

Good tip, thanks for sharing with us new owners.

Separately, have you guys noticed how the needle drops dramatically from F to 1/2 tank? In my 07, I'll go from F to 3/4 in about 30 miles, then to 1/2 in about 80 miles. Then the needle will float between 1/2 and 1/4 for about 170 miles. In all the cars I've owned, it's been the exact opposite -- the needle will stay near F for at least seemingly half the tank, then drop like a rock!

Of course, I'm still under 500 mi, so things may change as I continue to break it in. Have a great weekend!

jcalabria

Mine doesn't drop like that... it actually is very linear (unlike most other cars, which, as you noted, stay at "F" forever to make you think you're not using any gas), except that it all but ignores the lower third of the tank. When it nears "E" it will only take 12 gallons to fill, and when the low fuel light comes on there is a 1/4 tank of gas still in there. Good, bad or otherwise, its quite different than most cars' fuel gauge behavior.

At 500 miles you still have a way to go on the break-in. I really didn't see any improvement until about 4500 miles, then it creeped upward to what it is now. I think its probably done now, but it took 9-10k miles to get there.

HeavyDez

Thanks for the info. I've got 1900 miles on mine. What do you think about using a lower octane fuel? It seems like the high octane burns really rich. Tail pipes are smoking in warm weather. I tried a tank of regular and the car seemed fine and gas mileage was a little better. I don't want to ruin the fuel system with low octane. I've noticed the acceleration on throttle back too. I've noticed that if I don't throttle back on acceleration the rpm's will shoot up to 4000, while throttling back gets the same performance. This car accelerates very well from the 50 mph or so range. I never gun my car or off the line. I will push it to 4000 rpms from 50-60 mph once in while or cruise at 80 mph just to experience its power and smoothness, but I pretty much baby it. I love the CVT. It is very responsive. My wife loves it too especially when she's putting on her lipstick in the mirror.

DRod

Each time I fill up, it's between 20.0 and 20.5 gallons. Everytime I get a new car, I run out of gas twice on purpose to see how many miles I can go and position of the needle before it runs out. So I reset my trip odometer each time I fill up. Of course, it varies based on driving habits; but when I've been driving "spiritedly", I fill up sooner.

jcalabria

I am quite surprised that you got better mileage running regular gas. This is certainly not how it is supposed to be. The fuel consumption delta between regular and premium should run from virtually none to being in favor of the premium fuel, depending on how the car is being driven.

The engineers at Nissan (and other manufacturers) are not stupid. They don't create engines capable of utilizing higher octane fuel just so you can spend more money on feeding their cars. There are significant advantages to a high compression engine in terms of both power and fuel economy. All else being equal... creating a given amount of torque with a high compression engine will consume less fuel than doing so with lower compression.

The two main parameters the engine management system can use to control detonation caused by lower octane fuel is to either retard ignition timing or richen the fuel mixture. I'm assuming that retarded timing is the preferred method, but either of these should result in greater fuel consumption.

If the engine control system is retarding the timing much of the time due to the use of lower octane fuel in high load situations, it would be expected that the retarded timing would result in increased fuel consumption for a given level of torque output. The increased fuel consumption may, in fact, more than offset the cost of the premium fuel. The cost delta between regular and premium is not that great these days (it seems that its always a ten cent differential, whether gas costs $1.50 or $3.00 gallon)... if you save 4 or 5% on fuel cost but use 10% more of it, what are you saving?

My wife actually has a much heavier foot than I do... in all city driving she likes to put the pedal down at traffic lights and create high load situations for the engine. Particularly when she drives, we will typically see a 2 mpg difference depending on whether the car has premium or regular in it. That's about a 10% drop. Paying 5% more for gas that that you use 10% less of is a good deal.

Even the low rpm CVT economy technique I mentioned in an earlier post should benefit from the premium fuel... That technique is very much like short shifting a manual tranny and "torquing around" in high gear. That is one the worst possible pre-detonation (knock) scenarios you can have - high load at low rpm. I would imagine that that using regular fuel in that situation would also cause the timing to be retarded a significant amount of the time as well.

On the other hand, if you do mostly light-load highway cruising, you might not see much of a fuel mileage difference and the decision comes down to whether a few lost lb-ft of torque are important to you.

I'm open to learning something new if somebody can explain how lower octane fuel can increase fuel mileage, but right now I am not aware of any way that scenario would make any logical sense.

SilverMax_04

Your last phrase is certainly correct ("depending on how the car is being driven"), but the rest is not. Read the owners manual. This engine was designed to provide maximum performance running on premium gasoline, but to perform adequately on regular. The way you wife drives, you definitely need premium, as does any driver who frequently calls for WOT. Dez can get by on regular, and sees a slight increase in mileage doing so -- this is not surprising to me, but certainly will not happen for all Max drivers burning regular.

Auto Engineers make many compromises when designing an engine to give Maximum performance on premium gasoline, but also perform adequately on regular. You need to see the posts here in 6th Gen and in Fluids & Lubes from Max owners who have made modifications that increase their VQ's power -- and its need for octane. But a non-modded VQ will perform adequately (but not at the Maximum) burning regular gasoline. The VQ needs premium for any who want maximum performance in racing, on the dino, or simply beating everyone from the stop light (like your wife). If your driving style is such that you don't frequently call for WOT (Wide Open Throttle), then regular should perform adequately for you in your Max, you will save about 20 cents per gallon (10 cents for mid-grade and another 10 cents for premium), and you gas mileage should be about the same as it would have been burning premium. But this will not be the case if you burn regular and frequently call for WOT. You mileage will likely suffer versus burning premium.

There are actually three engine operating factors that determine an engine's octane requirement, but the "management system" can not control all three. Those factors are "Cylinder Pressure" (determined by outside air pressure and the possible use of a turbocharger), "Spark Advance" (the easiest for the system to control), and "Engine Temperature" (increasing fuel volume -- a richer fuel/air mixture -- can reduce the temperature inside of an engine, but this is not widely practiced due to environmental concerns). The easiest way to quickly reduce the temperature inside of an engine is to increase the engine's RPMs which increases both the air and the fuel flowing through each cylinder.

Octane Number is a widely misunderstood concept. I have attempted to explore this unknown in my posts on this thread in the Fluids & Lubes section of this site:
http://forums.maxima.org/showthread.php?t=396716

In the first post, I have a short table of contents, because there are so many aspects to the many questions about Octane.

This is certainly true as both high load and low engine RPM tend to increase the temperature inside the engine. This would be the only place I would expect Dez to experience engine knock while burning regular -- and if the engine control system has any effect on the CVT (I don't know if this happens, or not), the system may not let the CVT allow engine RPMs low enough to experience engine knock.

I defer to StevTec on this. Last year, I was doing an Interstate highway test to see if I could get better mileage by burning premium rather than the regular gasoline I normally burn all of the time. My results were slightly in favor of regular gasoline, but there were so many other factors that impinged on the results, it was hard to make any definite conclusions. Steve said that with the VQ cruising on the interstate with fairly high RPMs and not much load, regular should perform as well if not better than premium. In fact, Steve predicted that the mileage on the highway would be better burning regular. All octane does is burn slower and resist predetonation. None of this helps gas mileage when there is no need for these higher octane attributes -- like when you are highway cruising.

As long as you are not looking for peak performance, I recommend regular -- has not harmed my VQ with 52,500 miles of driving and only a few of those tanks were with premium gasoline.

I notice no loss in torque on the highway burning regular. And my VQ engine pulls very nicely burning regular and going around a corner in town at 1,200 RPMs in third gear. Steve also informs me that the control computer takes a few hundred miles to fully recognize a change in fuel octane level, so constantly switching between regular and premium will not allow the system to settle on a given octane level you plan to provide for your VQ.

jcalabria

I think on almost every point we are saying the exact same thing, but the variable in my equation is the constant in yours and vice versa. Were squeezing the same balloon at opposite ends.

It all depends on which factor is important to any person or a particular situation.

SilverMax_04

I disagree with this. We are talking applied physics, and this does not work. But when discussing the factors that the engine control system can modify to reduce engine knock, we are essentially talking about the same things -- but my points are slightly more accurate than yours (richening the fuel mixture is only one way to reduce the temperature in each cylinder -- with temperature being the controlling factor).

I certianly agree with this. With most things automotive, there are compromizes that have to be made. Figure out what is most important to you (or what you don't need to have) and then go for it (don't go for it). In the case of octane -- some people have to have the best -- let them pay for premium. For others like me, who don't call for WOT very often (I've done it about 3 times in 52,500 miles), premium is a waste of money and in the process yields slightly poorer highway mileage (per StevTec).

jcalabria

From www.fuelsaving.info The author is a UK automotive engineer.

Its a very simple...

• Certain engine design factors, such as turbocharging or higher compression ratios, can provide increased torque output but are inherently more susceptible to knock under high load conditions.
• These engines typically have sophisticated engine management systems that can sense this knock and compensate for it by retardng ignition timing.
• Higher octane fuel = greater resistance to knock
• Greater resistance to knock = more advanced ignition timing
• More advanced ignition timing = lower fuel consumption.

Which of these statements is not true?

All I have maintained from the start of this is if you operate your VQ under higher loads you likely will see a fuel consumption benefit from premium fuel. If you don't, you won't. Buyer's Choice.

You have made several statements that support this, yet we seem to be arguing over it anyway. I'm not sure why that is.

HeavyDez

This is an awesome discussion. You guys are allowed to have different theories from your research. I take a little bit from each persons insight and apply it to my own research. I'm not automotive mechanically inclined, so I'm learning alot from both of you. This is my first Max and my first new car. Again, great discussion. Thanks.

SilverMax_04

I feel a need to comment on this article from a British automotive engineer.

Outside of the USA and Canada, where octane is measured as (R+M)/2 (sometimes called "Octane Number" or even Octane), almost all octane is quoted as Research Octane (or RON for Research Octane Number), sometimes abbreviated as "R" (as in the above formula). To help you understand this engineer's points on gasoline octane, you can do a close approximation of our Octane to his RON by subtracting about 5 from his RON numbers: 98 RON is about 93 Octane, while 95 RON is about 90 Octane.

He makes a number of good points, which I would like to stress {and comment on in these brackets}.

- "are these fuels worth the extra money that they cost -- my answer is, 'it depends'."
{It always "depends" on many factors, including (but not limited to) each individual engine, engine deposits, individual driving styles, environmental conditions, etc.}

- "The effect of this {higher octane} on your car ranges from nothing to maybe 10% more power & torque, depending on the characteristics of the engine."
{Even the same engine in two identical cars can have slightly different characteristics that influence its need for higher octane. And don't forget the presence or absence of deposits in each engine -- which can increase octane requirements above manufacturer's design levels.}

- "being able to advance the spark at full load certainly gives better economy,"
{The key phrase here is "at full load". Without this load on the engine, the spark is not necessarily advanced and there is essentially no better fuel economy from premium than from regular. You approach full engine load when you call for WOT or when you climb a steep hill in a higher gear (something automatic trannies won't allow -- they down-shift).}

- "many engines run very rich at full load in order to cool down the exhaust gas,"
{While this does happen, it has a tendency to result in unburned hydrocarbons that must be disposed of in the cat converter. Also, the cat converter does not like the exhaust gas to be "too hot." But I believe there's another reason for the engine control system calling for a rich fuel mixture -- to cool down the cylinders and reduce engine knock.}

- "knock isn't an issue at part load, where the engine spends most of its time."
{This is a point I've been making from the beginning. Cruising the interstate highways at 75 MPH, where the VQ is turning over at about 2,750 RPMs, this engine is just loping along. It could easily handle this speed and load at 2,200 RPMs or less (requiring higher gearing from Nissan). Unless you need to frequently pass a slower vehicle on a 2-lane road (or climb a steep hill in high gear), you don't need premium on the highway.}

- "In terms of overall 'real world' fuel economy benefit due to increased octane rating, the effect is likely to be small unless you drive much of the time at high load."
{Correct, and with my driving style and VQ, I found the effect on fuel economy from burning premium on the interstates to be non-existent.}

- {He then goes on to explain who will need to burn premium gasoline}: "because you have an 'enthusiastic' driving style, or because you have a relatively large, heavy car with a relatively small but powerful (typically turbocharged) engine."
{The VQ at 3.5 L and without a turbocharger hardly qualifies as a "small engine," so only those who race (track or street) need premium IMHO.}

Based on all of this, I went back to see where jc and I were in disagreement. Turns out we were not really -- we were only stressing different factors more or less, like this on engine design:
- jc: "Nissan engineers have designed the VQ engine to take advantage of the benefits of burning premium."
- me: "Nissan engineers have designed the VQ engine to operate adequately on regular gasoline."

Even so, I still find a need to comment on jc's points, below:

They are all true, but the last one can be misleading. If you don't have your engine under heavy load, taking advantage of premium's ability to resist preignition, you will not get a fuel consumption advantage. If you do load it down, you will. So, cruising around town or driving the interstates while burning premium -- without calling for WOT (or climbing a steep hill in a high gear) -- should not provide lower fuel consumption than burning regular, because the engine does not take advantage of premium during these operations.

In fact, frequently calling for WOT will actually hurt your mileage versus driving more slowly (cautiously). So if burning regular will keep you from calling for WOT, your mileage might even be better with regular -- by getting you to change your driving style.

You are Correct, and I believe we are no longer arguing -- only stressing different points.

mayorez

I probably avg about 15 gal per visit. I like to fill up once I get below 1/4 tank. I never run it all the way down because you never know when you could get stuck in traffic or whatever.

Mr. Cummings

On E I have never been able to get more than 16 gallons in at a time. That little yellow light along with the * scare me into pulling over immediately.

I was under the impression that the maxima's fuel capacity was around 17 gallons. How are people getting 20 gallons in?

GhostDeany

always 16 gallons

SilverMax_04

If you check the Max's specs, you'll see that the tank holds 20 gallons. The early warning about low fuel level are to be certain that you don't run the tank down too low and expose the fuel pump (that's located in the bottom of the tank). This pump uses the gasoline to help keep it cool.

brrblackmaxed

...I don't want to slurp up the "dregs"!

SilverMax_04

The inlet for the fuel pump located in the bottom of your fuel tank is very near to the bottom of the tank. You are picking up "the dregs" all of the time you are driving, particularly when the fuel in the tank sloshes around.

You don't want the fuel level to get so low that the fuel pump overheats.

radwillie

15 to 16 Gallons for me, have never gone over that.

-radwillie