I really love the great handling, ride, features of my new M35, but I'm getting really lousy mileage. Anybody else have that problem with a new M35? It's got 900 miles on it. Does it take a wear-in time for the engine parts to loosen up or what? I don't think this should be the case. Hello?

Modern gasoline even without oxygenates-ethanolized is nowhere near the quality [BTU per gallon] of gasoline used by manufacturers to report to EPA city/highway MPG. Manufacturers have special custom blends produced to test HP/TORQUE and MPG for publication.

It is not their fault that you do not buy and use satisfactory fuels!

If you research you will find that 1985 gasoline averaged 120-123,000 BTU per gallon whereas todays products can be 104,000-110,000 BTU at best.

This was done to allow more gallons of gasoline from each barrel of oil!!!!

Also oxygenated/ethanolized fool the ecu into increasing AF ratio from 14.65 to 14.1-14.2 AF causing another 3% drop in MPG.

Failure to adhere with 50-60 mph max top speed [EPA highway test] and using AC and idling and generally not driving exactly as EPA test requires results in a 18-23% lower than published test data.

Not uncommon for todays gasoline to produce 10% less REAL ENGINE DYNO POWER than the manufacturers get using their special NORMAL BTU GASOLINE..............Ethanolized gasoline will reduce power by 2.8-3.7% [3.3% per EPA] ADDITIONALLY due to extra reduction in BTU AVERAGE.

http://www.chevron.com/product...onomy/ ... ct...shtml

Diesel has 129,800 BTU per gallon and has not be reformulated to decrease MPG due to it's use by trucks and the effect on transportation fees........cost of goods shipped........just allowed to rise naturally vs the hidden tax on automobiles. PLus the fully loaded rigs couldn't pull the loads up the existing hills with watered down diesel.

Hopefully you see that it is necessary to make conventional gasoline WORSE before 10> 85% Ethanol will be accepted by PUBLIC!http://www.e85fuel.com/forsupp...e.pdf

All that said, the M (35 or 45) sucks compared to other similar displacement cars. I routinely got over 22mpg (highway) and 16-18 (city) with LS400, E55, and E500's. I haven't seen that yet with my M45 after 5k miles. In fact, while many suggested that "summer" blends would improve my mileage, and I expected the further break-in and change to summer tires would also help, it's gotten worst. Averaging around 14-15mpg. Got 20 on a long trip (winter tires) in Feb and haven't seen that since.

To my mind, the mileage of this car is it's only big drawback.

My M35X is the worst car for gas milage I have ever seen. Its a V6 getting 17.6 MPG average. Poor job by Nissan/Infiniti.

On my 2003 M45, I average about 17 to 18 mpg with about 30% in-town mixed driving. With steady high-speed on the highway, I get a lot more. This is very comparable to what I used to achieve on my older Q45's and consistent with what other people told me about their LS400 and MB 400 models ...

Also, FWIW, mileage got steadily better till I reached 10k miles or so. Then it stabilized at what we see today.

One summer, we drove from San Jose to San Diego and back (fun trip to Legoland for my son), I drove around 75 to 85 mph (with occasional bumps to 90mph) for the whole trip and averaged about 24mpg or so.

Recently, I did a BG44K clean, because we seemed to be averaging about 16 to 17 mpg or so, and the mileage on the last few tankfuls has gone back up to the 17 to 18 mark. Clearly, cleaning injectors helps ...

Z

I cant believe this discussion is even taking place... We can spend upwards of 65k on a car yet we complain about fuel economy!!!!!!?

on a more helpful note, most nissan/infiniti get better mileage after a while like Z said... ALSO YOU CANNOT BELIEVE THE COMPUTERS! Figure it out yourself (miles/gallons)

Compare driving cycles of similar WEIGHT cars because it [fuel mileage] has more to do with weight than anything else!!!!! NEVER BELIEVE WHAT THE CALCULATORS SAY!!!!! DONT DO IT!!!!!! At least until you can see exactly how accurate they are...

I did a test of about 1000 miles of all highway driving on my parents grand prix GTP. All miles were done in one day, using cruise most of the time, with 98% highway..... The computer averaged about 1.5mpg MORE each time, with a high of 2MPG.. I reset the computer every time i filled up, with the trip meter...

unless you people ACTUALLY calculated the fuel economy yourself (you very well may have) and compared it ot the reading on the computer (resetting after every fuel fill up) then it doesnt matter. I cant guarntee but I certainly would assume that MB/BMWs will inflate fuel mileage.. 20 vs 24MPG is hardly noticeable if you dont keep track of miles but certainly has a large impact on the psyche.

Difference in a 24,000 mile year is about $50/mth and clearly climbing. Not enough to price the car in the 550 range, but pretty close given BMW's more aggressive lease rates. Not that I'd prefer the 550, though...

2000 miles @ 14MPG with 3/gal- $428.572000 miles @ 18MPG with 3/gal- $333.332000 miles @ 20MPG with 3/gal- $300.00

To be honest shattner, it may sound like something is wrong with your car... Its hard to say how good canadian gas is compared to american.. It may be apples and oranges, or it may not be....

Wess, I'd get it checked but typical service response will be "no trouble found" or "within spec". I'll wait 'til it's better broken in and we'll see. The mileage I was getting on the Benzes was also with our Canadian gas .

Now I'll admit to a lead foot with the M45, but then I also had one with the E55. The best mileage I've had in the M was with cruise control on at about 75mph.

Indeed.. but i still feel something is amiss, but maybe thats just how the M is..

What you could maybe ask them to do is perform a consult test and have them give you the printouts... I can then look at them and see if everything is truely in spec... This includes a power balance test...

Youll have them go to the data monitor on the consult iwth the car FULLY warmed up (driving for at least 15 mins) and then perform a power balance test printing all results

Mattx10x wrote:My M35X is the worst car for gas milage I have ever seen. Its a V6 getting 17.6 MPG average. Poor job by Nissan/Infiniti.

Listed average of the X is 18 city, 25 highway. 18 should be considered a mixture of stop and go with some "highway" style cruising. I do find it interesting that Infiniti lists 18/25 for both the M35 and M35X as I would think the M35X could get less mpg due to losses from the AWD drivetrain in comparisson to the M35 RWD only configuration.

Take a look at new proposed EPA conversion to reflect TRUE MPG vs the old 1985 test proceedure.

Actually you are correct in that Nissan has been using higher and higher and higher 5th gear ratios [via a higher diff gear] to increase the 1st/2nd gear ratios to improve acceleration at the expense of highway cruise MPG.

The orginal 5AT gear spread was designed for economy with a RWD V6 adapting this to a V8 and then trying to improve acceleration significantly reduced the highway MPG performance IF you exceed the EPA test speed of 55-60 MPH!

Nissan needs a 6-7 speed AT to compete as 5AT was yesterday's news back in 1998-2000.

Interesting comments on "tight" 5th gear ratio on the M. This is definitely the case - my '03 E500 had a 5AT and wound about 20% lower in 5th. Also interesting is that it seemed to have more "punch" in passing range (2nd / 3rd) although the M45 is quicker off the line.

So a 6AT should definitely help lots in the consumption dept.; seems it won't be an '07 item, though.

Nissan does not currently have a 6AT transmission. It is the one bad fault of the car.

The 5AT also can't handle the full 300 HP of the high end 3.5 V6, like the 6MT can. That is why you only see the 280 HP engine on cars with the 5AT.

Talking about gas mileage, my previous car was a 2004 Audi S4 Avant, 340 HP V8, 6MT, which was had the poorest gas mileage of any wagon sold in the US. The gas mileage on the 6MT was less than the 6AT and made you pay extra for the poor mileage, something you did not have to do with the 6AT. I used to average around 14 MPG city and highway. I'm very happy with the mileage on my M35X.

scjconsulting: I just purchased my M35X and am also from Mn. I live near Grand Marais so I realize there is usually more snow up here. My question is: Did you have the M this past winter? If so, how was it in snow? Thanks!

I bought it in later February and you know that there was almost a complete lack of real winter around the Twin Cities after Xmas. Any snow I drove through was no problem and I am not planning to get snow tires like I used to get for the S4. You might think about snow tires along the North Shore!

Enjoy your M35X up there!