Is there any way increase MPG for M45?

[adwpm45s]

I had my M45S for a year and half. MPG is really really disappointing. This is gas guzzler!I get 14-15 MPG usually except highway MPG is little better about 18-19MPG.Is there any way i can improve MPG except change your driving habit like start slow, speeding 60mile...etc.

[Q45tech]

Purchase a higher BTU per gallon gasoline that does not contain ethanol should improve things by 3.3%.Change the rear differential gear set from the gas hog 3.313 to ~ 10% less for a 10% improvement in MPG.

[mexillis]

you can also buy a near cat back exhaust for a little increase in MPG and it will sound better

[hawkfan]

Purchase a higher BTU per gallon gasoline that does not contain ethanol should improve things by 3.3%.Change the rear differential gear set from the gas hog 3.313 to ~ 10% less for a 10% improvement in MPG.

Would this work for the M35 as well? You're essentially changing the final drive ratio right? That would seem to be the answer to improving highway mileage at least. I'm looking at both an 07 M35 and M45 right now. The M35's real world mileage is "acceptable" but the M45 is down right awful. I keep hearing quotes of 15-17mpg which is really thirsty. The M35 fares a little better but the achilles heel appears to be highway mpg which can hopefully be fixed by a different rear diff gear set. I'm wodering if there are any readily available replacements out there for the M35/45 though.

[M45Runner]

There are several way to do it:

1. Reduce the weight - take out back seat and passenger seat. Remove the GPS unit and all the equipment around it. Also, don't forget all the sound deadening materials.2. Disconnect the spark plugs and fuel injectors for every other cylinder. Or better yet, replace the engine with a 4 cylinder - after you have removed enough weight.3. Install a solar panel on the top of the car and electrical motors on each corner of the car, so the solar panel will generate powers to move the car instead using gas only.

If the above does not work, sell the car and get a Civic Hybrid, that will for sure cure the problem..

Just playing with ya, man.

[fiveliterbeater]

buy a beater.......that's what i'm doing......

im getting ready to pull the trigger on an SRT-4 neon

[mcrews]

Wow...some really bitter members I have a 2002 Q45 Sport w/ 183,000 miles. I consistanly get 25+ mpg on the road.1. exhaust system: removed rear suitcase muffler (wiehged 25lbs) running two glasspacks. Replaced single pipe resonator w/ x-cross pipe. left center factory mufflers. car is barely louder than stock.2. run 255x45x18 on stock 18 rims instead of 245. 3.4% more diamiter giving lower rpms at hwy speed.3. Custom built lower intake for stock air box.4. drive with the mpg screen on at all times5. change oil & filter every 3k

[Q45tech]

The 2002 Q45 ALREADY HAS an economy rear differential ratio which was increased in 2003 to give better acceleration!

The 2002 2.76 is quite a bit different from the 3.313 of the M45 we were discussing, 20% different in fact and I would expect ~~ 20% better MPG on 2002 Q45...................the 4 MPG difference is perfectly borne out in tests.

Important for member to understand engineering difference before they compare differnt years or models [weighs].

CAT back exhausts won't improve MPG any as the system is controlled by O2 sensors and RPM

[adwpm45s]

Thank you for your advise, but is there any simpler solution???Like using cetain brand gas or change certain air filter.......

[antzrus]

Thank you for your advise, but is there any simpler solution???Like using cetain brand gas or change certain air filter.......

Yeah, next time do not get a luxury sports sedan that was never meant to be a gaz miser; but a luxury sports sedan. Zoom-zoom (pardon me Mazda) costs money!!

Come on fellow-these M lists on the internet make the poor gaz mileage far from a secret. The demographic for an M is not someone w/out a lot of $$$ for such a machine. Possibly your eyes were bigger than your stomach!

[odie]

Doesn't Michelin claim to save up to 104 gallons of gas using a certain tire?

See! I knew I saw it on TV so it MUST be true:

http://www.youtube.com/watch?v=HF_I68jCwHg

[UpStar]

Thank you for your advise, but is there any simpler solution???Like using cetain brand gas or change certain air filter.......

The answer is simply NO! You got exactly what you paid for. 16-20mpg is what you can expect +/- 1, so why complain when this was clearly noted. V8 330+ horse powered cars are not designed for fuel economy, so I suggest you sell it and buy a 4cyl honda civic. Sorry

[adwpm45s]

QUOTE=adwpm45s]I had my M45S for a year and half. MPG is really really disappointing. This is gas guzzler!I get 14-15 MPG usually except highway MPG is little better about 18-19MPG.Is there any way i can improve MPG except change your driving habit like start slow, speeding 60mile...etc.[/QUOTE]Nissan shouldn't put 5 speed automatic for 8 cylinder car!!!!!!!I wasn't really focus on MPG or other details when i bought this.M45 S those 4 letters made me blind....... Are we getting 6 or 7 speed automatic for 2011 model?

[adwpm45s]

Yeah, next time do not get a luxury sports sedan that was never meant to be a gaz miser; but a luxury sports sedan. Zoom-zoom (pardon me Mazda) costs money!!

Come on fellow-these M lists on the internet make the poor gaz mileage far from a secret. The demographic for an M is not someone w/out a lot of $$$ for such a machine. Possibly your eyes were bigger than your stomach!

But my friend's 2008 Lexus LS460 get better mileage than mine.I believe he got 7 speed automatic.

[adwpm45s]

The answer is simply NO! You got exactly what you paid for. 16-20mpg is what you can expect +/- 1, so why complain when this was clearly noted. V8 330+ horse powered cars are not designed for fuel economy, so I suggest you sell it and buy a 4cyl honda civic. Sorry

i am complaining for Nissan's misjudgement. they shouldn't put 5 speed automatic.

[UpStar]

i am complaining for Nissan's misjudgement. they shouldn't put 5 speed automatic.

I wasn't really focus on MPG or other details when i bought this.

Im fcuk'n done reading this post

[antzrus]

But my friend's 2008 Lexus LS460 get better mileage than mine.I believe he got 7 speed automatic.

Well yes, he got a Lexus, you got an Infiniti. Come on bro. What did you want-buy? You got what you paid for-just as I did.

Don't need no Lexus stats- I gotta' Infiniti!!!

[ken in az]

The 2002 Q45 ALREADY HAS an economy rear differential ratio which was increased in 2003 to give better acceleration!

The 2002 2.76 is quite a bit different from the 3.313 of the M45 we were discussing, 20% different in fact and I would expect ~~ 20% better MPG on 2002 Q45...................the 4 MPG difference is perfectly borne out in tests.

Important for member to understand engineering difference before they compare differnt years or models [weighs].

CAT back exhausts won't improve MPG any as the system is controlled by O2 sensors and RPM

Couple things here

1st - 2002 Q45 is rated at 16cty 23hwy by the fedshttp://www.fueleconomy.gov/FEG...shtml

and the difference of the rear diff change was a 1mpg reduction only at hwy as the 2004 model is rated at 16cty 22hwyhttp://www.fueleconomy.gov/Feg...shtml2nd - and it's really no big deal but the M45 rear diff ratio is 3.357:1

Sometimes Q45tech the math doesn't always work out as you'd expect.

3rd - a cat back exhaust is a proven method for increasing fuel economy on many different vehicles just not too many on the 2006 M45. The reason is that the exhaust efficiency increase allows an engine to create more torque at lower rpms requiring less throttle opening to achieve the same speed and sustain. This is a function of increase of torque not a function of closed loop ecu functionality and feedback control from the O2 sensors.

I personally average 20-21mpg with mixed driving which is easily 2-3mpg better than what it was before I started modifying the intake and exhaust. Interestingly enough I was able to achieve the best fuel economy with the worst performing intake where it was intaking the hot underhood temperatures.

My personal best - watching the mpg gauge on the screen and maintaining vehicle speed between 60-72mph depending on incline or decline - Over a 67mile commute with mixed city - 20% hwy 80% - 27.2mpg per dash gauge.

[ken in az]

To bounce off my last post - Exhaust and intake gains are usually not warranted because of the cost incurred with the purchase and installation of said items.

Best thing to do is to maintain your tire pressure and watch, watch, watch, and I mean WATCH your mpg screen gauge everytime you drive. That alone will save you easily 1-2mpg depending on YOU the driver.

Also, don't be afraid to pop the trans into neutral and coast for a while. There are certain sections of road where I can pick up about .5 - 1mpg just by coasting downhill. There are even specific places where if I hit the lights just right I can coast for nearly 2 miles "with" traffic and still only hit the brakes.

There are other extreme practices you can do such as "hyper-mileing" where in those downhill sessions you can even shut off the engine and gain even more mpg's.

Another thing is to simply park it and get a beater like fiveliter said - an old diesel rabbit that gets 50mpg lol and they were made in the 70's hint hint prius drivers you all arent that inovative.

Then finally the most effective way to increase your mileage is to carpool. Effectively halving, thirding, or quartering your fuel costs typically you can consider you fuel economy to double, triple, and quadruple depending on how many passengers you carpool with. If you get 18mpg then with 1 passenger you now have a 36mpg beast. 2 passengers you now have a 54mph monster. And at 3 passengers you now have a 72mpg elite green car!

[M45Caliber]

here, here -- I second what Ken has said I drive my M45 HARD -- that's why I bought it. However, late last Friday nite, my daughter called for a ride as her battery died. So it's 1am, and I decide to take a local surface street that has no traffic and lights every mile (some times a light at the 1/2 mile too - Ken would know this street - Warner... east from Priest Dr. out to Higley, and back) So I wanted to see what I could get mileage wise, fo kicks.

Got to the first light and reset the trip computer. Drove at about 8 or 9 over the 45 MPH limit the whole way (11 miles each way) and maybe had to stop 4 times each direction. I was light on the throttle and coasted, sometimes in neutral, if a light changed to red and I was still 1/4 mile or so away. When I parked it I had managed 23.3 MPG for the 22.5 mile R/T. It wasn't any FUN driving it that way - BUT - if it's mileage you want, it CAN be done. BTW -- a steady 60 on the FWY nets a little over 25mpg, if you can drive that slow.

[kingpin]

Well i will start by adding my input , and i am sure i will have a few people up set with me by the time i am done so here goes !

If you were looking for better fuel milage and an eco friendly car you should have gotten a leaf . please do your reasearch before making a purchase gas was never the issue ,but here is what hapened to me and how my fuel milage improved .

I got a JP muffler when i got my bodykit ..so i had to modify that to fit my Y34 , When i went to the shop they found one of my muffler leaking , The price for new one was out of this world at that point (from dealer),i decided to open the car up exhaust and get rid of all the factory stuff so here is what i have ..

2 Cats Y pipe into 3"inch stainless into a high flow RES. then straight to the Jp muffler on the rear ..i was averaging 20 mpg on hwy i am at 26 mpg @ 98kmph. I am going to build a true air intake over the winter so hopefully that number will go up by 1mpg.

My worst fuel ecomomy was 6.1mpg (-45) and my best was 26.3 Mpg (+22) that was running only 94 octane .

here is a simple tip to help run you climate control only when necessary and use your sun roof Vs your door windows .

[Sentientbydesign]

You bitter members are douches!

To the OP, your fuel economy is on par with my G35. 2 less cylinders and 1 liter less displacement.

My suggestion is that you reset the ECU, then drive conservatively. Eventually, the car will adapt (to a degree). The differential is definitely a cause for the poor fuel economy. My G is at 3k rpm at 80 mph. On my I30 with the smaller VQ30DE (and FWD), I would cruise at 2700 rpm at 80.

[mcrews]

Couple things here

1st - 2002 Q45 is rated at 16cty 23hwy by the fedshttp://www.fueleconomy.gov/FEG...shtml

and the difference of the rear diff change was a 1mpg reduction only at hwy as the 2004 model is rated at 16cty 22hwyhttp://www.fueleconomy.gov/Feg...shtml2nd - and it's really no big deal but the M45 rear diff ratio is 3.357:1

Sometimes Q45tech the math doesn't always work out as you'd expect.

3rd - a cat back exhaust is a proven method for increasing fuel economy on many different vehicles just not too many on the 2006 M45. The reason is that the exhaust efficiency increase allows an engine to create more torque at lower rpms requiring less throttle opening to achieve the same speed and sustain. This is a function of increase of torque not a function of closed loop ecu functionality and feedback control from the O2 sensors.

I personally average 20-21mpg with mixed driving which is easily 2-3mpg better than what it was before I started modifying the intake and exhaust. Interestingly enough I was able to achieve the best fuel economy with the worst performing intake where it was intaking the hot underhood temperatures.

My personal best - watching the mpg gauge on the screen and maintaining vehicle speed between 60-72mph depending on incline or decline - Over a 67mile commute with mixed city - 20% hwy 80% - 27.2mpg per dash gauge.

NOTE: I also run 44 psi when on the road. 37 in town.Ken,Thank you so much for being "smart enough" to 'see' OUTSIDE THE BOX!!! Frankly Q45tech your post read like Maxnix edited it for you.

The point, which clearly you missed, was that given ANY FXXKING CAR, you can do things to improver milage I wasnt comparing my 02Q45 to his M45.......I was trying to show that given some thought, there are some things he actrually can do.Hell, just driving w/ the info screen on the mpg is worth 2-3mpgs on the freeway.....(I mean, it is an 07 M45 and has a mpg info screen...right..... not some 1990 beater infiniti????? )And The damn thing has tires right??? so if he wan't to go up 10mm to improve the final drive ratio.....he can do that.... right??? ANd running a little more psi in the tires will tweek some posters on NICO, but hey....

As ken pointed out, I'm beating the epa hwy number consistantly. That's the whole point.

Frankly, my point on the muffler has to do with weight..... Surely the 2 rear muffler setup on the Ms must wiegh 30-40 lbs??

So before you starrt lecturing: """Important for member to understand engineering difference before they compare differnt years or models [weighs]."""""

.......maybe it is important for you to get a grip and understand that my post is a honest look at the op question

As a final thought, Sentientbydesign is correct about ECU. My style of driving is much more conservative than 3 yrs ago. The ECU has adjusted to that. I never the first away from the light.

My last trip to texas (1700 miles in 2 1/2 days) average speed was 69.8 and the mpg was 26.1. I was carrying 2 FX 20 rims and a full trunk. A/c on the whole way.

[StevenRogers]

change oil before the 3000 mile mark. i didnt realize that really keeping on top of changing the oil on time maintains fuel economy. we had been driving the m45 for about 2,800 miles into the last oil change and the mpg monitor dropped significantly. we averaged 18. 3 city and 20-25 hwy after an oil change. as we got closer to the 3,000 mark our mpg dropped so bad that i thought there was something wrong with the car or the electronics. it had dipped into the high 15s city and 19-20s hwy. after an oil change, the car was back to normal.

popping the car in nuetral is a good idea too. on my way home from work, i can get about 10 miles in on neutral. i work at 3000 ft above sea level and live at sea level.

[kingpin]

True i run a thicker grade 10/40 and its has stopped buring oil ...

Try running sea foam it works wonders for mpg

[fiveliterbeater]

I cant believe every single one of you guys completely ignored his sig!!!

the guy owns 6 cars! the solution to better MPG is driving a car that doesn't suck down that much gas! PERIOD!

i can't believe everyone is getting in on this circus act of trying to get the M45 more fuel efficient when clearly....the M45 delivers alot and gives ALOT more than the average luxury car in its class, and in return, only uses just a bit more fuel!

...and to the OP, i can't believe you're trying to compare our machine to a Lexus whose MSRP was originally $89,999. for that amount of money, the car better have a built-in rectal-thermometer

lol

[ken in az]

Oddly enough I switch my tunes on about a monthly basis - which everytime I switch the tune It clears the ECU Learning and restarts from zero. I notice no difference in mileage from day 1 to the last day I have it in there and I don't think anyone has the ability to clear the learned fuel trims without a service tool like Cipher or Consult or equivelent. Please let me know if there's any other software out there that can do this.

[antzrus]

I cant believe every single one of you guys completely ignored his sig!!!

the guy owns 6 cars! the solution to better MPG is driving a car that doesn't suck down that much gas! PERIOD!

i can't believe everyone is getting in on this circus act of trying to get the M45 more fuel efficient when clearly....the M45 delivers alot and gives ALOT more than the average luxury car in its class, and in return, only uses just a bit more fuel!

...and to the OP, i can't believe you're trying to compare our machine to a Lexus whose MSRP was originally $89,999. for that amount of money, the car better have a built-in rectal-thermometer

lol

Ditto...

[ken in az]

NOTE: I also run 44 psi when on the road. 37 in town.Ken,

Since I pay alot at the pump for fuel - I pay alot of attention to things that affect fuel economy. Tire pressure plays the most role in fuel economy more than anything I have whitnessed on this car.

I have played with tire pressure quite a bit since this is the first car with TPMS that I have owned.

33psi - Great soft ride, speedbumps are barely noticable, MPG's fell about 2mpgs with that pressure. Tires would heat up on the freeway to about 39psi meaning tire temps were a little excessive which corrolates to more friction and more rolling resistance and less economy.

35psi - Slightly firmer ride but still nice, MPG's down about 1mpg - 1.5mpg, Tire temps still managed to get up to 38psi, This means that the rolling resistance was a little less than before at 33psi but still enough to cause a dramatic change in pressure.

37psi - Firm ride, feels like I added a stiffer shock absorber to the car but not excessive, still smooth on the open road but can definitely feel cracks in the road that I couldn't before, glove box started to rattle - lol, Tire temps rose to 39spi on the freeway which is only a 2psi rise, this means that rolling resistance was considerably decreased and better for fuel economy, Best for fuel economy on my vehicle so far.

38psi - Tire temps rose to 40psi on the freeway, no noticable improvement on fuel economy, Tire pressure reduced to 37psi to maintain the best wear characteristics for the tire. At $300 a pop I don't want to prematurely wear these bad boys out.

40psi - Trackday with Infiniti of Scottsdale - Tire pressure rose from a 20min session to 42psi - not bad - except for the rear driverside tire which rose to 43.5psi because is was the inside tire on the track and was doing most of the spinning - lol

Haven't tried any higher pressures, but theoretically you can go as far as the MAX cold pressure rating on the sidewall of your tire and be safe from the tire exploading, but this may not be the best for handling nor the best for tire wear. Adjust at your own risk

[rsg123]

37psi - Firm ride, feels like I added a stiffer shock absorber to the car but not excessive, still smooth on the open road but can definitely feel cracks in the road that I couldn't before, glove box started to rattle - lol, Tire temps rose to 39spi on the freeway which is only a 2psi rise, this means that rolling resistance was considerably decreased and better for fuel economy, Best for fuel economy on my vehicle so far.

Thanks for that post. I adjust my tire pressures occasionally and always thought that testing out different psi vs mpg at the same time/road conditions would be a great idea. I will try 37 and see if my mpg improves (it's already good at around 21-22 60/40 hwy/city).

Regarding the OP, why do you immediately rule out changing driving habits? No matter in what type of conditions you drive, there are always little changes you can make to improve mpg/wear and tear without taking away the fun. The 22mpg I mentioned before includes daily full throttle passing and quick accelerations from lights. I think driving habits and tire pressure are the easiest and most effective ways to improve mpg in your M.