MPG Concern on newly purchased 07 M35

[SIK L]

Guys,

I just purchased an 07 M35 Sport recently. I see that the NEW MPG ratings are 16/23 based on fueleconomy.gov. On my status screen, it shows average MPG at 19.5. I made a highway trip on a full tank of gas and only got around 320 miles to the tank, which would break down to 16mpg (based on 20gal tank). Do you guys have any recommendations on how I can improve my MPG or if there is a known issue that I could look into to give me better fuel economy? I have almost brand new tires and I rarely open the throttle up past 50%.

Any input would be greatly appreciated. Thank you in advance!

[goM35]

The M's drink alot of gas. It has to do with the weight of the car, large engine, and IMO the gearing on the 5 speed transmission. Notice your RPM's are in the 2600 ish range when cruising at 60+ mph. That's too high if economy is your target, which the M is not about. If the transmission had more speeds or a better ratio overdrive, then the mileage would (in theory) improve. The newer models have a 7 speed and I wonder what type of mileage those are getting?

There's no way else to describe the low MPG. I've had mine for 18 months and once got 21.5 all highway at 65mph using cruise and by feathering the gas. Take your time going from a stop to 65mph, coast when coming up to a red light and generally drive under the speed limit in local traffic-all while watching the realtime gas gauge on your dash. Now that's the exception, and not practical for eveyday driving. If you drive like I normally do, you'll average 16 city and 19 hway.

If it helps, I use 87 Octane and am not sure what kind of boost 91 or better would achieve. ??

[Ilya]

Are you sure the tank is 20 gallons? I know that is the official spec but I've filled up with like 20 miles left and I've only been able to put in almost 17...figure if you get 18mpg that's another gallon. I'm thinking our tank is 18 gallons, not 20.

[LVdennis]

I wouldn't use the computer window for your final assessment of mileage. Start with a fill tank of gas and write down your starting mileage. Keep track of how much gas you put in at each refill and fill to the top at the end of the test. Then calculate miles driven and total gas used. Divide the gas used into the miles driven. That will give you the exact mileage. This car is a performance luxury sedan. As such it gets good gas mileage. Most people don't have the ability to look at a computer display of ESTMATED mileage at a glance. That mileage will vary at every acceleration you make. Try wiping the mpg while you’re driving down the road slowly. Then after a fast start and you'll see what I mean. Relax and enjoy one of the BEST luxury sedans out there. Good Luck,
Dennis

[EniGmA1987]

If you all get that low of mileage with highway driving then maybe you are driving wrong? Before I did any mods to my car I could get around 26mpg highway driving on level ground. My longest trip without filling up was to Vegas and back which was a total of 460 miles (229.91 miles each way), I did that on a single tank of gas. But I was literally on empty at the end of it. I filled up 2 streets away from my house instead of the one right by me because the mileage estimate said I could go **.* miles more. lol

And no it definitely is NOT a 20 gallon tank. Most I have ever put in was 17 gallons and that was with about 1 bar left on the gauge.


Rarely opening the throttle up past 50% could be a problem as that could be killing your mpg. Also you need to know what speeds to cruise at that get the best mileage. And you need to learn how to make the most use of dips and hills in the road to minimize your time on throttle at the hills. You also need to be able to read traffic so you dont have to stop and then accelerate while driving on the freeway in light-moderate traffic. Oh, and dont use the cruise control ever. It sucks and will get worse mileage than you driving yourself

[The00Dustin]

And no it definitely is NOT a 20 gallon tank. Most I have ever put in was 17 gallons and that was with about 1 bar left on the gauge.

I've put 18 gallons in my 2006 M45. I've never driven a vehicle where the needle didn't go well past E before you were out of gas, so one bar left and 17 gallons doesn't even come close to making it definitely not a 20 gallon tank. I don't know whether or not there are any rules that would prevent a manufacturer from providing bad information regarding fluid capacities, but I can't imagine any reason why Nissan would do so regardless. The fuel economy screen going to **** and the low fuel light being on mess with you and make you want to fill up, which is a good idea considering that it can be bad for your fuel pump and engine to actually run out of gas (fuel pump sucking air = bad for pump, more junk in gas getting to fuel line b/c you ran it empty = bad for engine). That said, I don't know how much gas one should keep in the tank for best fuel pump longevity when driving daily, but I will say that I personally would probably have ended up putting more gas than that in my tank by now if it weren't for the fact that it is difficult to fill, so I don't trust it to be full even if it is capable of holding 20+ gallons. I believe the fluid capacity measurements aren't supposed to include the space in the tank for air (to allow the gas to expand) or the space in the filler neck (where there is obviously gas as well), so I'd say it is technically capable of holding more than 20 gallons, however,it's a saddlebag type fuel tank, and there's no guarantee that the half on the opposite side of the car from the filler neck is actually full to capacity when the neck fills up, not to mention most gas stations don't have level pads next to the pmups, and that affects your ability to get it full too.

[SIK L]

Try wiping the mpg while you’re driving down the road slowly

How do you wipe the MPG reading from the status screen?

[LVdennis]

It doesn't cost any more to keep the tank full. I think it's best to keep it full for several reasons. Condensation will accumulate, and cause water in the fuel system. I live in the desert and didn't think about the tank being full or not. You never know when an emergency will arise and you'll need a full take to get where you're going. To clear the MPG turn the selector wheel to MPG and delete it. Good Luck
Dennis

[mdstahl]

I also own a 2007 M35. I drive 65 miles one-way to work each day, all highway, so I'm pretty conscience of my fuel consumption. I average around 21.6 or 22.1 for just about every tank I fill up (2X a week). I've run it nearly empty once or twice and have never gotten over 17 gallons pumped, so I just assumed it was an 18 gal. tank. I did notice that if I kept my tires inflated in the 31 or 32 psi range that knocked my mpg to the high 20's. I keep them at 35 or 36 psi now. Also always run premium in it (93), so I don't know what 87 will do. I'm going to try a fuel system cleaner (probably Redline), as I'm interested if I see any difference. My ride is mostly level with a few moderate hills. RPM runs over 3K rpm as I'm usually cruising at 79 or 80 mph - If I can find someone to run with me, I'll cruise at well over 90mph - fuel economy typically does not change all that much.

Interestingly enough, I've had my car in the shop for the last 4 days - they hooked me up with a loaner 2011 M37 - nice! My M35 had an ticking/rattle in the headliner in front of the sunroof that turned out to be a broken spot weld (frustrating as hell!). Anyways, the 7speed is nice the new M as it keeps the revs down and I've noticed MPG in the 23 range for the same commute. Around town its been a bit lower as I've been pretty sporty with the throttle - it's quite fun to drive.

[Lynchr]

I bought my 06 M35x three weeks ago and just returned from a 1,200 mile trip from Nashville to Myrtle Beach and back. Most of this route is far from flat and includes driving through the Smokey Mountains. Set cruise on 75 mph (about 3,100 RPM) for 90% of trip. Round trip fuel average was 21, with a one tank high of 22.4. Mileage determined by dividing gallons used into miles driven.

As an aside, this car handles great. I went through the mountains (on interstate) on cruise at 75 mph. Even on curves that were posted for 45 mph. Cornered so flat and smooth that my wife didn't notice how fast I was going (and that is saying a lot). I got the car with a fresh set of Bridgestone RE960's on it. The adaptive cruise control is a PITA.

The facts:
1. The M tank holds 20 gallons of gas.

2. The gas gauge is not an accurate indication of fuel remaining in the tank.

3. Trip computers have improved from the early days and are fairly accurate but not the definitive measure of mileage. They use throttle position, RPM, manifold vacuum, and other parameters, to calculate MPG. They do not measure the volume of gas consumed.

4. Fuel pump nozzles vary in their cut-off sensitivity. On some fill ups I have been able to nurse up to two more gallons into tank after pump clicks off. If you do not care to do this, then check your mileage by filling up at the same pump (not just the same station) and calculate your mileage. Hint: reset one of your trip odometers each time you fill the tank.

5. Dividing gallons pumped into miles driven since prior fill up is the only accurate way to determine consumption.

6. To determine the distance you can drive before empty, multiply your MPG times tank capacity. For example, if you calculate you are getting 20 MPG, then the range on a 20 gallon tank is 20 MPG x 20 gallons = 400 miles to empty. This has nothing to do with what the gauge says. This does not apply if you are trusting the pump to fill the tank before it shuts off on it's own.

2 ~ 6 Applies to any vehicle, not just Nissan/Infiniti.

[myother45isalesbaer]

I have found on my older M I get 18-23mpg depending on city or highway driving. The on-board mileage calculator on mine is pretty accurate. As several posters have suggested the only way to measure true mpg is to fill the tank. I let the pump stop on its own and don't over fill it. Drive until you fill up again. At that point make sure you know how many miles you went. The pump will tell you the gallons used. Do the math. Make sure your tire pressures are at factory specs. I have also found on long trips my mileage goes up or down depending on if I am decreasing elevation, generally going downhill or increasing elevation, going up hill. On a 300 mile trip I have noticed a 2mpg difference. Many other posters have some good tips. I use all of them. Another thing I noticed is exceeding the speed limits does not seem to have much effect on my mileage. I often run in the 70-90mph range. General wisdom says I should get less mpg's. My wisdom tells me I an running the engine/trans combo at their more efficent range of rpms and speed. Don't recommend it, but my M seems to love running between 80-90 and well beyond.

[themacs]

I Have an '09 M 35 (with 7 speed trans of course). I normally get an average of 20 MPG overall. On an all freeway run, I get about 24 mpg.

Sometimes these #'s are better or worse but this is an average.

I am not heavy footed.

[goM35]

IMO, the gas tank is 20 gallons, but does not fill to that level. It's most likely affected by air pockets in the tank, so when I fill it up, it will only take 16-17 gallons when on empty.

Enigma-would love to know how you get 26 mpg??

[Lynchr]

IMO, the gas tank is 20 gallons, but does not fill to that level. It's most likely affected by air pockets in the tank, so when I fill it up, it will only take 16-17 gallons when on empty.

Please read my post above. The gas gauge is not accurate. Manufacturers intentionally calibrate the fuel sending unit to show less fuel than is really remaining to insure driver will fill up before running out of gas. On my 06 M35x I can only add 17 gallons too when the gauge is on "E". That means there is still three gallons in the tank.

If you need to prove this to yourself put a five gallon can of gas in the trunk and dive until the engine dies. Put the five gallons in and drive to the nearest gas station and fill it up. Add your five gallons plus the amount pumped and see what it totals.

I was on the road for over ten years (50,000 + miles per year) as a factory rep and would routinely refill the tank with less that 1/2 gallon remaining. I still do this for all my vehicles by using the mpg and tank capacity to determine range. Use the trip odometer to monitor miles driven.

Example: Determine mpg over several fill ups by dividing miles driven by gallons used. Lets say you are getting 21.4 mpg. We have a 20 gallon tank, so:
21.4 x 20 = 428 miles. You can drive 400 miles and still have over a gallon, or 20 miles, left in the tank. If you use the gauge, then you think you can only go
21.4 x 17 = 363.8 miles.

It's really not wise to run the tank very low because the gas is used to cool the in tank fuel pump, and you want a safety cushion for unforeseen circumstances, but is a bind you can travel a lot further that you think.

[06M4.5]

I try my best never to go less then 1/2 a tank if I don't have too.

[sergio1987]

I know I suck, but I always fill up full and wait until the fuel gauge lights up:)
I live in Toronto, and for those who don't know, it is an extremely congested city, and obviously I drive mostly during rush-hour...so maximum 10 km.h(yes, we do it in km, not miles:)))) )
and considering this I average 13 l/100 km...that is about 18 mpg ( M35X). WHICH I DON'T MIND!!!! This is a luxury vehicle with LOTS of extras to add to the weight...but if you can't afford it, buy a Jetta or corolla, it will make you happy.
No matter what, I LOVE the car!!!! Just today I was driving around, about 200 km trip ...and i decided to check which car I would switch my m for, not considering the value of both cars..The only cars that I would consider even changing the M to are just brand new C,E,GL,S MB, BMW X5, 7and 5 series...and THAT'S ABOUT IT!!!Toronto is one of the richest cities in the world and still I could be driving for 30 min without seeing a vehicle that would come even close to question my love for the M.
Hope that helps, and if the gas kills you, try getting a points card from some gas station, like ESSO...I get about $10 every two weeks worth of gas for free:)

[SIK L]

Would using 87 octane (or anything less than 93) affect MPG? I normally wouldn't think so, but since purchasing the vehicle a couple weeks ago I've filled up a couple times with 93 and the MPG seems to be improving. Maybe the previous owner or dealership was using 87 and it made the MPG temporarily lower?

[m4m]

Guys,

I just purchased an 07 M35 Sport recently. I see that the NEW MPG ratings are 16/23 based on fueleconomy.gov. On my status screen, it shows average MPG at 19.5. I made a highway trip on a full tank of gas and only got around 320 miles to the tank, which would break down to 16mpg (based on 20gal tank). Do you guys have any recommendations on how I can improve my MPG or if there is a known issue that I could look into to give me better fuel economy? I have almost brand new tires and I rarely open the throttle up past 50%.

Any input would be greatly appreciated. Thank you in advance!

Have you checked your air filters (there are actually two), keep your tire pressure at about 35 PSI all round, regular oil changes, use premuim grade gas and see if it worth to pay more to get more miles (it works for me!) and take out any unnecessary things out of your car...
HTH

[bbs350z]

Are you sure the tank is 20 gallons? I know that is the official spec but I've filled up with like 20 miles left and I've only been able to put in almost 17...figure if you get 18mpg that's another gallon. I'm thinking our tank is 18 gallons, not 20.

its the same with the z. they have roughly 3 gallon reserve tank so the cars dont get stranded on the side of the road. its dumb dumb proof lol.

as for achieving more mpg, do bolt on mods, such as intake, manifold spacer, etc so the engine works easier, and the added benefit of freeing up power. your mpg will go up a bit as well, as i noticed when i originally got my z. i was getting about 30mpg freeway on 93 pump at 55-60mph.

factor in the car weighs 2 tons, and has a high output v6, which is outdated btw, as the m35 are still using the original de version of the vq.

if you have an x, and are considering lower gearing, keep in mind that the transfer case and rear diff have to mesh up in sync. both parts need to spin at the EXACT same speed otherwise you risk ruining 1 or both.

[gavnator]

I use tier1 93 Octane, inflate the tires to door specs, and service all filters and fluids to most critical Infiniti recommendations. 16.5 MPG city, 23 MPG Hiway

[EniGmA1987]

You could try inflating the tires to the tire specs instead, if you have something besides the factory default Goodyear RS-A's

[LVdennis]

I believe inflation specs on tires are to give the user the maximum weight and speed at the maximum air pressure. This is not at all related to the car they're on but only for the tire. So if you inflate your tires to the maximum allowed on the sidewall you may carry the maximum amount of weight allowed on the sidewall. Automobile manufactures suggest an air pressure rating that is optimum for their car. If you inflate to the maximum you may notice that the center will wear sooner than the rest of the tire. They may ride ruff and not have the grip you expect and need. Good Luck

[EniGmA1987]

I didnt say inflate it to the maximum your tire can go did I? Of course I dont think you should inflate the tire all the way to the maximum the tire can hold. Im just suggesting that if the tires max pressure is something like 54psi, you can get better gas mileage without wearing out the center of the tire prematurely by inflating the tire to 38-40 psi.

[MasterFoo]

I wish I had the MPG you guys are getting. my "07 is getting 11-12MPG At least 20 would be nice.

I just added Lucas Fuel System Cleaner, it improved a bit. All my tires are at 36 psi. Anything else I should be checking to get it at least to 20mpg+? Are spark plug misfires common in our engines?

I plan on changing the air filter with a K&N and a oil change next. Is it OK to SeaFoam an M35?

[gavnator]

Look, all of this is conjecture unless we are driving under the same conditions, have the same wear and tear, and service records. That's not the case. I don't care what M your driving 35 or 45, X or non-X. These cars are rude on fuel and I hope you looked into that before the purchase. An M35X, assuming it's been serviced regularly and on a diet of good premium fuel should not be getting 11-12 MPG.That's wrong. I don't service my M. I let Infiniti take care of it. Let me give you some advise on tire pressure. You don't need 36 PSI in you tires. As someone previously posted, it depends on what you have on your car. I have Y rated performance tires on my M (yes there summer tires) and the performance and handling dynamics are totally difference from an all season. I go by the door sticker. So does Infiniti and the tire dealer I use. Yes. I own an M35X but I also own a Pathfinder so when it snows which vehicle do you think I drive? You did not say if you purchased you M from an Infiniti dealer or not, but if your getting that kind of milage city or hiway somethings not right. I don't know where your located but you may want to check with the forum and find a local recommended Infiniti dealer to do a general checkup. They can also pull up any Infiniti service record on the car since it when into service. LOL.

[szh]

(Off-topic post, since we did deviate a bit above.)

Setting at the manufacturer's tire pressure is not a bad thing to do, of course, but not necessarily great advice either. While higher pressures will reduce rolling friction, thereby increasing mileage a tiny bit (less of an effect than having too low a pressure), the resulting harsher ride and uneven tire wear may end up being being a good thing.

Comments:

1. People often set their pressures warm (after driving a few miles for example). This is not a good thing, since the recommendation is for truly cold settings. That means you should set the tire to the required value when the car has not yet been driven in the morning - if you have a garage, check it before you pull out into the sun (black tires absorb heat).

2. It is normal for tire pressure to drop 1 or 2 psi over a few weeks to month. If you are not diligent about checking the pressure, starting at mftr recommended 33 or 34psi will make it low after a few weeks. So, imho, it is better to err on the high side rather than on the low side to allow for these periodic drops.

3. Gauges are not always the most accurate - so, again, it is better to err on the high side a bit.

4. Measure and adjust at least once every other week - certainly don't wait for more than a month, and if the weather has changed a lot, then check it sooner.

5. Do get a tread depth gauge - they are incredibly cheap (the penny and quarter measurement techniques are silly to do frankly!). I have one in the glove compartment in both our cars. Using this to measure the depth at various points across the width of the tire will give you an indication of how the wear is going.

6. Do get a reasonably accurate pressure gauge. Good digital's and good analog ones are perfectly fine - just avoid the cheapo pencil gauge if you can. Repeatable measurements are necessary to be able to properly adjust pressure up or down ... adjusting for wear.

7. Do get a home pump (electric is easiest) if you can - best to pump the tire up in your garage at home in the mornings when the tire is still cold.

Ideally, the best way to find the right value for you, is to start at the value used for tire load index tests (this value is 36 psi). Then go up or down 1 psi at a time, accurately, over time to find the right compromise between safety concerns (too low), road harshness (too high) and evenness of tire wear across the tread (with a tread depth gauge). During this period, measure at least once a week and correct the pressure accordingly.

When increasing or lowering the normal set pressure during this period, don't go below the 33 or 34psi recommended by the mftr, or above - for that matter, anywhere near - the max indicated on the sidewall (should be 50 or 51psi for our modern tires). Frankly, if you find yourself setting the normal use pressure well above 42 or 44psi, then you are probably experiencing a harsh ride and/or not measuring wear properly.

Hope this helps!

Z

[MasterFoo]

Look, all of this is conjecture unless we are driving under the same conditions, have the same wear and tear, and service records. That's not the case. I don't care what M your driving 35 or 45, X or non-X. These cars are rude on fuel and I hope you looked into that before the purchase. An M35X, assuming it's been serviced regularly and on a diet of good premium fuel should not be getting 11-12 MPG.That's wrong. I don't service my M. I let Infiniti take care of it. Let me give you some advise on tire pressure. You don't need 36 PSI in you tires. As someone previously posted, it depends on what you have on your car. I have Y rated performance tires on my M (yes there summer tires) and the performance and handling dynamics are totally difference from an all season. I go by the door sticker. So does Infiniti and the tire dealer I use. Yes. I own an M35X but I also own a Pathfinder so when it snows which vehicle do you think I drive? You did not say if you purchased you M from an Infiniti dealer or not, but if your getting that kind of milage city or hiway somethings not right. I don't know where your located but you may want to check with the forum and find a local recommended Infiniti dealer to do a general checkup. They can also pull up any Infiniti service record on the car since it when into service. LOL.

I did not buy it from an Infiniti dealership it was from a Luxury used car dealer. It was a lease vehicle according to the Carfax, but I'm not sure how it works with lease vehicles and maintenance records. Is it mandatory? If I can I have an Infiniti dealership look it up in a database, great.

I'm in Northeast NJ, I'm making the call to the Service Dept. tomorrow at the closest Infiniti (Fette Infiniti). I just wanted to make sure I'm prepared so that I do not leave anything out. It is very strange that I'm getting such horrible MPG and I've been researching and bumping threads to get as many answers as possible as to why it may be. I'm not new to cars but I am new to cars with warranty and dealing with dealership service departments.

Thanks for the advice

[gavnator]

If you take the car in for servicing (let's say and oil change) and they've never serviced the M before they should pull up all service records associated with the vehicle. They will tell you where you stand according to the different Infiniti service tiers. If they don't, request a service history report stating you want to know where you stand on service schedules. You did not say what the milage was on the M but if it's an '07 your probably due for some milestone fluid changes anyway. Did you buy in state or in the tri-state area (CT, MA,NY)?

[MasterFoo]

If you take the car in for servicing (let's say and oil change) and they've never serviced the M before they should pull up all service records associated with the vehicle. They will tell you where you stand according to the different Infiniti service tiers. If they don't, request a service history report stating you want to know where you stand on service schedules. You did not say what the milage was on the M but if it's an '07 your probably due for some milestone fluid changes anyway. Did you buy in state or in the tri-state area (CT, MA,NY)?

Just got off the phone with the nearest Infiniti dealership, they pulled the service record and it seems like the previous owner had not taken it in to service since Feb 2009 for I believe was the 26,250 maintainence. I made an appointment with them for next week to do a diagnostic ($109) and hopefully get to the bottom of the MPG issue.

It was purchased in NJ, the mileage on the car is just over 49,2XX the warranty is good until June 2011. And I will be extending with Elite it for sure (not sure if I should wait?). After doing some investigative work, she (the previous owner) didn't really take care of the vehicle mechanically. The service manual is empty but there was a letter from a Service Manager advising her to bring it in as soon as possible. I will say the interior is immaculate and all the electronics work just fine. Hopefully I can obtain all the proper TSBs before my trip to the dealership so that I'm prepared.

So far I have the:
Driver seat play/movement 1/2-1inch
Corroded/Seized TPMS nut

Thanks for all your help Gavanator

[EniGmA1987]

Just cause Infiniti doesnt have a record of service done doesnt mean it wasnt done. Most people I know have their own mechanic do maintenance on the car cause it is a lot cheaper than the dealership.



Also, I am in the process of finding my average mileage with only minimal extreme driving. So far it is looking like I average 20mpg with both mixed freeway and streets. Sitting in the drive through for 15 minutes every day really kills the mileage
I average 27-30mpg on my way home from work, and 21-23mpg on my way to work every day.
22mpg with actual driving on streets, and drive throughs for lunch and dinner then drop my mpg down to about 14 average cause of all the sitting.

Now I am doing an average from 2 tanks worth to see what it is without resetting it during that time. And I do have pictures to prove it all.


EDIT: oh and this is after my 2 degree timing advance, gear change that makes me run higher RPMs than the rest of you, and my wheels out of alignment. And just passes 100,000 miles during this little test