Current MPG

[DeanM45]

I know there are a lot of posts out there regarding mileage for the M45.

Thought I'd share mine.
2006 M45S with Megan cat back, custom 2 1/2" to 3" Y pipe, Injen intake, UpRev tune, lowered with Eibach Pro, factory rear spoiler, Mobil 1 5W30, Red Line synthetic rear end fluid and transmission fluid (try at your own risk but I have had no problems), transgo shift kit, external trans cooler, 40 psi tire pressure (cold).

On highway trips with minimal traffic where I can maintain 72mph I get around 30mpg.
Around town it drops to 21mpg with a combined average for me (30% city, 70% highway) of 26mpg.

The shots below are from a trip down to Diego today. Tires are obviously hot and the average MPG was just before I filled up again. It took 16.7 gallons and showed 517.7 miles which comes out to 31.0 MPG so the computer is slightly optimistic but not too far off.




This has been the norm for the past 5 tank full or so. Biggest improvement was doing the UpRev tune and then resetting the learned fuel trim (using Cipher). Car really loves the highway. Cruising at 72 give or take, ac on, windows and sun roof closed. I also slightly lowered the target idle rpm to 525 which helped in stock and go and idle states, no impact to charging or cooling with the lower idle and still smooth.
The performance is great and the mileage not too bad. Make the motor/drive train more efficient and everything increases.

[EniGmA1987]

Pretty good for an M45 My v6 engine can get right about the same without tuning and mods, but it is a much smaller engine. I think this makes you the highest MPG person on these forums.

[rxmclaren7]

well unless you consider the hybrid guys......i am getting about 23mpg on the hi way...if i remember to reset my MPG computer when i fill up for just around town driving i avg 17 mpg

good job dean on you mpg's i plan on getting the megan midpipe and the axle back exhaust and do a tune as soon as i can afford it all!!!

[Ilya]

WTF?

I get 22mpg @ 75mph on the highway. Maybe 23. Tires at around 40psi (hot).

I have also tried the clearing of learned fuel maps via Cipher to no avail. I'm also meticulous with my maintenance so all of my fluids, filters, etc. are clean. The only thing I haven't done is change my O2 sensors. Could new ones give me ~7mpg? Really?

I just hit 100k, and know I needed to do my O2 sensors soon anyway so I just bought all four. Hopefully my mileage goes up.

[EniGmA1987]

WTF?

I get 22mpg @ 75mph on the highway. Maybe 23. Tires at around 40psi (hot).

I have also tried the clearing of learned fuel maps via Cipher to no avail. I'm also meticulous with my maintenance so all of my fluids, filters, etc. are clean. The only thing I haven't done is change my O2 sensors. Could new ones give me ~7mpg? Really?

I just hit 100k, and know I needed to do my O2 sensors soon anyway so I just bought all four. Hopefully my mileage goes up.

Southern California air density, climate, gas, and roads are way different than New York. AZ guys can get some really great highway MPG too. So you may never be able to achieve these sorts of numbers where you live, no matter how meticulous you are on maintenance and mods.

[DeanM45]

WTF?

I get 22mpg @ 75mph on the highway. Maybe 23. Tires at around 40psi (hot).

I have also tried the clearing of learned fuel maps via Cipher to no avail. I'm also meticulous with my maintenance so all of my fluids, filters, etc. are clean. The only thing I haven't done is change my O2 sensors. Could new ones give me ~7mpg? Really?

I just hit 100k, and know I needed to do my O2 sensors soon anyway so I just bought all four. Hopefully my mileage goes up.

Uprev and exhaust. O2 sensors can definitely have an impact on mileage as they are the primary source for the ECU to perform fuel map trims. When you reset the trim with Cipher the LTFT should go to zero. After driving for a bit, what are the new LTFTs? If the numbers are high on one or both banks then the O2 sensor(s) are probably dying (when they fail they typically fail in a "lean" mode so more fuel is dumped in).

[The00Dustin]

WTF?I just hit 100k, and know I needed to do my O2 sensors soon anyway so I just bought all four. Hopefully my mileage goes up.

Give an update after you replace them. Especially since you can clear fuel maps with the cypher. Maybe that is why my mileage dropped and it isn't because my tires feel like they have suction cups on them, after all, I do have like 150K miles on the thing, but even if I tried replacing the O2 sensors, I'd have to learn the trims back down by driving, no cypher for me.

[Ilya]

You would just need to clear the ECU and that would reset everything. The Cipher is just an easier way.

[atlM35]

Great numbers!
I'm already seeing improvement after a few days of the Y pipe work.
Sounds like another reason for me to get a tune.. hopefully in the near future.

[The00Dustin]

You would just need to clear the ECU and that would reset everything. The Cipher is just an easier way.

Makes sense, still wouldn't mind hearing how it works out for you first. I think my exhaust kinda smells like sulfur (fireworks sulfur, not really strong raw eggs sulfur). I never noticed that with any other car of mine, could I potentially need new cats too? No point in putting in new O2 sensors only to destroy them.

[Ilya]

Yes, a smell like that might mean cats.

I will definitely let you know once I get the sensors and install them. I think they'll be here next week.

[DeanM45]

You would just need to clear the ECU and that would reset everything. The Cipher is just an easier way.

Makes sense, still wouldn't mind hearing how it works out for you first. I think my exhaust kinda smells like sulfur (fireworks sulfur, not really strong raw eggs sulfur). I never noticed that with any other car of mine, could I potentially need new cats too? No point in putting in new O2 sensors only to destroy them.

The sulfur smell is a very good indication that the O2 sensor(s) are bad (assuming that your air filter is in good shape). Scan to see what the secondary O2s are showing. With everything warmed up they should be in the .28volt range.

[cruzad3r]

i seriously have no idea how on earth those with v6 actually get more than 20mpg combined driving. my best mpg during the summer is around 19.x and it's frikin 15.x now in the winter.

i have motordyne 1/2 spacer with the armid coolant spacer and greddy cat back.

[Ilya]

Same here. My typical driving is around 19.5mpg mixed. I just don't get it.

[Larz]

You know what gets me? I was out early this morning about 6am on the way to the gym. No cars on the streets as its a Sunday. On the road I used, there are stop lights at intersections, but they will only cause me to get a red if a car is waiting to cross. So .... I set the cruise for 45 which is the limit (cops are awake and alert at 6am Sunday), reset the mpg screen, and my mileage was astounding! I was averaging 26mpg (roads are flat here in FL) SO here I am with a wide smile on my face, Coldplay blaring on the surround, and ....... BAM! The drawbridge goes up to allow a yacht to pass. What felt like 10min later, the bridge comes down, I drive on and check the mpg and well, %$@#$% FORK ME %@$#%$ !!!

[Ilya]

Best way to get mileage is over a period of time, not after one fill-up and one reset of the screen. That's usually off by a mile or two.

Here is a picture of 3 months (since the new year) of my mileage. It SUCKS.

BTW, this is the aCar app on Android if anyone is wondering.

[cruzad3r]

Same here. My typical driving is around 19.5mpg mixed. I just don't get it.

wait, didn't you say you got 22mpg from post above?

[Ilya]

Same here. My typical driving is around 19.5mpg mixed. I just don't get it.

wait, didn't you say you got 22mpg from post above?

The picture above is mixed, 22 is on the highway (100% highway, if I take a 5hr trip somewhere for example). The log above is of my daily driving to work, school, etc.

In the summer, I average about 19.5mpg on the same roads. Winter fuel plus temp differences gives my what is in the image (this is from Jan 8th to present).

[cruzad3r]

that makes sense. @ constant crusing speed about 80MPH and less, I can get up to 22 MPG on the freeway on long distance trip. other than that, it's definitely less than 20MPG combined driving.

[EniGmA1987]

Do you drive yourself or with cruise? Cause the cruise control will give you terrible MPG.

[Ilya]

Almost always myself.

[Logan00]

Do you drive yourself or with cruise? Cause the cruise control will give you terrible MPG.

I never use the cruise control but always thought it was the opposite, using cruise would improve mpg since the speed is consistant......

[Ilya]

Cruise is only MPG-beneficial on extremely level roads. If there are hills, cruise becomes a bad thing because the computer keeps adding gas and coasting once it hits the cruise limit. Here in the North East, we don't have many super level highways. Down I-95 in say SC, GA, or FL...cruise becomes very efficient.

[Logan00]

Thanks Ilya, that clears it up for me

[mazz]

I know there are a lot of posts out there regarding mileage for the M45.

Thought I'd share mine.
2006 M45S with Megan cat back, custom 2 1/2" to 3" Y pipe, Injen intake, UpRev tune, lowered with Eibach Pro, factory rear spoiler, Mobil 1 5W30, Red Line synthetic rear end fluid and transmission fluid (try at your own risk but I have had no problems), transgo shift kit, external trans cooler, 40 psi tire pressure (cold).

On highway trips with minimal traffic where I can maintain 72mph I get around 30mpg.
Around town it drops to 21mpg with a combined average for me (30% city, 70% highway) of 26mpg.

The shots below are from a trip down to Diego today. Tires are obviously hot and the average MPG was just before I filled up again. It took 16.7 gallons and showed 517.7 miles which comes out to 31.0 MPG so the computer is slightly optimistic but not too far off.



trying not to sound like an old man , but i have driven infiniti since 1990 from q45 thru two different model m35 and have not approached 30 mpg , but i never did the mods to the car that you have so i will refran from calling BS.I have averaged around 22 mpg over 200,000 miles in m35 mostly highway travel , what issues if any are you finding running air pressure on tires up to 40 PSI when cold i run 35 i thought that was high???

This has been the norm for the past 5 tank full or so. Biggest improvement was doing the UpRev tune and then resetting the learned fuel trim (using Cipher). Car really loves the highway. Cruising at 72 give or take, ac on, windows and sun roof closed. I also slightly lowered the target idle rpm to 525 which helped in stock and go and idle states, no impact to charging or cooling with the lower idle and still smooth.
The performance is great and the mileage not too bad. Make the motor/drive train more efficient and everything increases.

[DeanM45]

mazz wrote:
trying not to sound like an old man , but i have driven infiniti since 1990 from q45 thru two different model m35 and have not approached 30 mpg , but i never did the mods to the car that you have so i will refran from calling BS.I have averaged around 22 mpg over 200,000 miles in m35 mostly highway travel , what issues if any are you finding running air pressure on tires up to 40 PSI when cold i run 35 i thought that was high???


No issues at all aside from a slightly firmer ride which I do not mind.

[mexillis]

OP how many miles can you get in a tank?

[DeanM45]

OP how many miles can you get in a tank?

I usually get between 430-460. Best I got was 496.
Keep in mind that this is not some miracle car or anything like that. When I do dumb things like taking on a challenge for who could make the longest pair of parallel stripes the mileage goes to WAY less than that. I won BTW, spun them through most of third for a total of 28 feet.

[EniGmA1987]

trying not to sound like an old man , but i have driven infiniti since 1990 from q45 thru two different model m35 and have not approached 30 mpg , but i never did the mods to the car that you have so i will refran from calling BS.I have averaged around 22 mpg over 200,000 miles in m35 mostly highway travel , what issues if any are you finding running air pressure on tires up to 40 PSI when cold i run 35 i thought that was high???

35 really isnt high, most tires that are supposed to go on this car say 50-something PSI max. The Hankook Ventus V12 EVO tires that I use are 54 PSI max. Doesnt mean you should run them like that, since you do need "wiggle room" for heatup during driving and also the compression of the air when you hit a bump at speed, but you can easily run 40 PSI cold in most tires these days. The higher PSI helps your gas mileage quite a bit too. A study was done a year or so ago and it showed that increasing either 1 or 2 PSI (cant remember) improved MPG by 5% or something like that.

And while many probably do think this MPG is BS because they cant achieve anything close, I still think the main difference is west coast vs east coast drivers. The average person with these cars on the west coast just seems to get more miles per gallon than any average east coast driver.

[mexillis]

I forgot to ask which map are you in?