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Infiniti G35 Real World MPG



  • Engine running except for possibly 5-10 minutes out of the 52 hours. Except for pauses in traffic, at red lights, and during startup, I don't spend any time idling.
  • Last fill up I got 22.3 MPG wit 80% highway and 20% city. Been using only 91 and the car just broke 1100 miles, hopefully it keeps getting better! :P
  • sweendogysweendogy Left lanePosts: 1,299
    409 mile trip from boston to nyc and back.. cruse engaged for half the trip of mostly highway miles.. avg 22.8 (23 on the trip computer) . I tryed to run the tank (93 octane)completely out as the warning light went on, I have noticed that the warning light goes on when there is 3 gallons left in the tank. I ran the car for 25 miles with the light blinking and the scary **** showing up on the nav screen-- filled up and put in exactly 18 gallons -- why does the screen go blank when there is roughly 50 miles left on a tank?? on long cruses this car is terrific
  • pscheidpscheid Posts: 190
    sweendogy........Your experience with fill-ups and the is pretty much the same as mine. The 04 Coupe has a (stated) fuel capacity of 20 gallons. When the low fuel warning light goes on, the tank will take on about 16 gallons. At distance to empty-------, it will take about 18 gallons to fill, meaning you still have some fuel in there.

    My mechanic advised not to run the tank down to ------- which is 0 miles to empty. The in-tank fuel pump uses the fuel to remain cool. Other than make sure you never run out of gas, that may be the reason for all the advanced warnings (light and DTE) protect the fuel pump. If you ever had to get a new fuel pump in a car where the gas tank has to be dropped to replace it, you many want to think twice about running the tank down to DTE-------too many times. Expensivo!

  • pscheidpscheid Posts: 190
    durangojay......hope your car has been repaired successfully by this time.

    You noted you live in Colorado at an elevation above sea level of 6,600 feet. You might find some interesting information in your owners' manual under "Fuel Recommendations." There is a subsection about operating the vehicle above 4,000 least there is in my 04 Coupe manual.

  • pscheidpscheid Posts: 190
    durangojay or anyone......

    My 04 G35 Coupe's owners' manual states a fuel recommendation, not a fuel requirement. Is that because the 306hp and 330hp engines actually require a higher octane rating? Could you check your owners manuals on that?

  • sweendogysweendogy Left lanePosts: 1,299
    JACK--thanks for the post..interesting stuff -- i still think 2-3 gallons of gas should not be considered a low tank--i hear you on the fuel pump issues . ..thanks for your input and durango lives in Co.. he crashed his car and got its being fixed in --wait for it--Durango Co.. loner car-- a dodge durango--hope that helps
  • At the risk of going off car is almost ready. Thursday or Friday hopefully. It has taken about 21 man-hour working days to repair. No major frame damage, which is good. Thanks for the great posts. I get nowhere near what you guys are getting in city MPG. Will continue to post MPG after I get the car back. And yes, I really did get a Dodge Durango rental loaner covered under insurance. Weird, but true. p.s. Cannot wait to get back in that sweet ride! :sick:
  • johninnjjohninnj Posts: 243
    Congrats ! ! !
    Look at it this way....after that'll enjoy your G's MPG lol
  • You are spot on, John. I just read most of the recent posts. Some responses: I will be switching to a tire, year round, that is more geared toward wet/slush/snow. I will give up a bit in performance, but feel more secure. Also, thanks for the heads up about the fuel recommendations section in the manual. I don't have it now, obviously, but will check it out when I get the vehicle back. Perhaps I will be switching octane grades after all this. However, I seemed to have been getting excellent performance so far with a premium grade. Stay tuned. :sick:
  • pscheidpscheid Posts: 190
    First, your journey is nearly complete and the car will be back in your hands Friday.....great news.

    Second, I was wondering if at your altitude of 6,600 feet above sea level that the altitude and rarified air has a negative impact on the fuel economy. Engine management systems can and do adjust the fuel/air mixture to accommodate for the reduced oxygen in a given amount of air by adjusting the fuel component. This is more of a "protection" adjustment to prevent detonation and control engine operating temperatures. But completely overcoming or compensating for the reduced oxygen content? I don't think so. I would expect fuel economy and acceleration stats to be adversely affected, regardless. Someone who knows more about this stuff than I us out here.

    Finally, if you are looking for an all season tire replacement instead of snows, you may want to read my thread on the G35 Coupe in the snow. Main Topic: INFINITY G35 COUPE Subtopic: G35 Coupe in the snow. Guys with RWD and AWD Infinities and other makes have responded with their experiences and recommendations, some tire brand and tire model-specific. I have a RWD Coupe, live in MA. (snow), and am looking to switch to an all season alternative myself.

    Have spent considerable time on the NTB website reading tire owner survey opinions, 13 different road condition stats, and expert road tests with a concentration on Infinity and BMW owners' experiences.

    My choice at the moment is the Bridgestone Potenza 960, and about 100 pounds in the trunk during the winter snows. While winter tires would be optimal, I can't bring myself to dedicating a $1,400+ set of rims and tires to accommodate the half dozen days a winter where I might get 6+ inches and road crews falling behind. Then I have to buy a new set of tires $900+ next March for the Spring, Summer, and Fall.

    At the rate the G Coupe chews up tires, irrespective of one's driving habits, it is looking like MPG and fuel expense is not far ahead of tire expense on the concern list.

    Some folks don't worry about total ownership expenses (taxes, insurance, depreciation, fuel mileage, tires, reliability/repair associated expenses, etc.). Some do.

    When you pick up your car, don't forget to bring the searchlight and magnifying glass to examine the repairs. Bring an anal/retentive nitpicking friend along too.....they can be helpful once in a while. ;)
  • Thanks for the good words. I do feel that the altitude may have something to do with my reduced gas mileage. Other than look in the manual for suggestions and read helpful posts here, I don't know what to do. The body shop doing the work is absolutely top notch, but I will take your words under advisement. Unfortunately, most of the work performed is WELL above my comprehension. The best I will be able to do will be to check out the paintwork, fit and finish, take it for a drive, etc.
    As I have AWD I am not going to get snow tires, per se. Just something with a little more wet grip. I ran my OEM tires through a horrendously heavy snow year last winter and I was quite pleased with the results. So a small upgrade would be just the ticket. Thanks again. Jay. :sick:
  • After 70,000 incredibly enjoyable miles...around town between 23-24mpg and on the highway (70-75mph) 27-28 mpg using 89 octane half the time, 87 the other half.
  • pscheidpscheid Posts: 190
    Yes, but how many tpg (tires per gallon)? Even my Corvette didn't go through tires like this car. :)
  • 2007 G35x finally back from the shop. Still a couple of minor odds and ends need attention, but she rides like a dream. No more SUV's for me. Unfortunately, mileage is still the crappy mileage it was before, but such it the price of a sports car. I'll definitely trade MPG for performance any day. :shades:
  • pscheidpscheid Posts: 190
    Gas was probably about 30% more expensive the last time you drove it! :)
  • HA! You're probably right! That is at least one good thing out of this! Ahh, the FAST feeling is back!! :shades:
  • sweendogysweendogy Left lanePosts: 1,299
    for those looking to talk mpgs -- last recording is 21mpg mixed driving (80% highway) --just under 11k miles on 2007 G-X
  • paulo6paulo6 Posts: 94
    I got 2000 miles now on my 2008 G35xS, I drive short distances but once in a while I do longer HWY miles (40+ Miles). Of course I drive the car hard at times like it should be driven. But at times I make it a point to drive extra gently, even coasting a lot in D, but I cannot seem to get more than 300 miles/fill-up (17+ gallons)...that is no where close to the MPGs I am reading about here with NORMAL day-today driving. I use only premium. OK, it is 30 degrees now in Michigan already, but still...

    Trip computer averages 16 or so MPG and it seems to be pretty close to actual
  • pscheidpscheid Posts: 190
    First. New car tolerances are tight, very tight. You won't see your car's best mileage until after it's broken in and it has a substantial number of miles on it. I spoke to a retired mechanic yesterday, and he observed that some may not see a car's true "top" mpg until 10,000-15,000 miles, perhaps more. I routinely get over the EPA 26 mpg highway on my 04 Coupe's (30,000 miles on the odometer).

    Second. I've read in Edmunds and other places that the best fuel economy for cars lies within the 45-55 mph range. All things being equal, that's primarily due to wind resistance. Above 55 mph, wind resistance takes more than a simple straight line, algebraic toll on fuel some point, for example, an increase in cruising speed of 10% will take more than a 10% toll on fuel economy.

    That is why a G35 will hit 155 mph (electronically limited) with 280-330 hp. But take off the electronic speed limiter to achieve 200 mph? The G and other cars would need to double the horsepower to gain that last 45 mph! Read Car mags' annual 200 mph shoot-outs. 500 horsepower isn't enough! You can translate that increase in required power and fuel consumption for small incremental top speed drops all the way back to 55 mph.

    Third. You are driving an awd vehicle. I would assume that with the extra weight and more moving parts (versus my rwd Coupe), your mileage will always be 5%-10% less than a lighter car rwd G with less moving parts.

    Now would be a great time to get a basis point for your car's (highway) mileage. I would suggest you take a 100 mile uninterupted joy ride on cruise at 60-65 mph once the car is warmed up, light or no traffic that would disturb your test. Set the cruise and reset your mpg once at cruising speed and that's it. Leave the accelerator alone! If it becomes necessary to disengage the cruise and then re-engage, stay EASY on the accelerator to get back to speed. I'll bet with your new car that isn't broken in that you'll still see 24mpg or more. Once broken in, the car is very capable of meeting or exceeding the EPA highway number.

    In the city, pure city driving, another story. I have to baby my car to get 18-19 mpg. One blast from a stop light and the mileage begins it's plummet. Simple aggressive driving (not all out), and the mileage plummets. I get 15-16 mpg with MY normal city driving style.

    The accelerator and your right foot hold the key to higher fuel mileage. I've written in other threads here that fuel octane (91-93 versus 89) has had no discernable effect on my fuel mileage. As for developed horsepower from an engine when changing octanes/fuel grades......Check out the Hundai web site. They provide horsepower and torque differentials for the new Genesis at varied octanes. The difference is surprisingly quite small. Off the top of my head, 1.5-2%!

    So if you want to see higher fuel economy figures, the answer is in the break in, speed, vehicle weight, and your driving style.

    There is no shame in resisting that accelerator. So few of us, however, drive the G for fuel economy. But it is nice knowing the car CAN achieve the city and highway fuel mileage the manufacturer claims.

    On a vacation this past August I got around 27 mpg to get to my destination, and somewhere around 13-14 mph tooling around. My son in law was stunned at the difference and asked what happened. "My right foot, that's what happened." :D
  • johninnjjohninnj Posts: 243
    My 07 is just as bad. I blame the gearing primarily...with, of course the right-foot issues like the other post. I had a friend with an 05 coupe 6mt...and he did much better on the highway. Infiniti raised our redline to 7500, then took the liberty to adjust the gears accordingly. I would be interested in a post from someone with the new 7sp auto. We have a VERY good aero design (And even have a belly ban under the engine), but spinning a 3.5 liter that high on the highway HAS to burn real way around it.
    My car has's gotten slightly better. I actually did better on reg than premium...but that one still escapes me.
  • paulo6paulo6 Posts: 94
    Thanks for feedback, but again I am comparing to other posts with AWD (added weight)...I will wait and see what happens next summer when the weather warms up and my car gets broken-in more. But with 15 years in automotove industry experience, etc. I just cannot imagine these factors can improve my MPG from 17 now (This is with EASY driving intended to see how high of an MPG I can get - If I drive my car NORMALLY I am lucky to hit 15) to lets say 23 MPG as a lot of the posts indicate...thats a 35% improvement!!!!

    In the meantime I will continue to experiment (Higher MPGs) and have a blast with my G (Dismal MPGs)...
  • sweendogysweendogy Left lanePosts: 1,299
    my thoughts on mpg-- i drive a 2007 g35 X -- my mpgs have increased a bit as the car has aged --just 11,300 miles on a car thats over 1.5 years old and i have seen mpgs of just over 17 for the life of the car ( I got the car with 20 miles on it). I must admit most driving has been city. Now what i've found-- city mpgs are terrible --but thats the norm on such a car with a 5 speed auto and high HP.. past post are right the new transmission of 7 speeds should help..I think the 300 lbs of the awd hurts mpgs-... The 5 speed is not the best trans --for sure-- the maxima and altima are cars born on the same platform and get way better mpgs then the rear drive G (with less hp --to the drive wheels.) .. I changed my driving habits as gas hit the 4 (and more) dollar mark here in MASS.. but now that gas is back down under 2 bux here I will drive the car harder and will sacrifice MPGS to get to 80 mph faster.. If your looking for MPGS --its easy -turn off your V1-stay , stay off the gas and use cruise control on the highway. I can tell you this -- I have started using the manual mode more and have found the sounds delightful coming from the back end of the car.
  • sweendogysweendogy Left lanePosts: 1,299
    600 miles this long thanksgiv weekend.. 2 fillups -- 23 and 23.4 on each. 90% highway with average speed of 65mph (according to the computer). used premium on my first fill up -- regular fuel on the second-- have not seen a difference in performance or mpgs.

  • sweendogysweendogy Left lanePosts: 1,299
    car has now 13k miles on it --its an 07 g35x --mpgs have kind of flatlined.. 2 fillups one premium for 1.79 a gallon then regular at 1.47 (thank you south jersey) the mpgs for the first tank were 22 mpgs-- now mind you this was going south from MA to NYC 200 miles at around 42 avg mph during a snow storm. -- second tank going at an avg of 60 on the way back from the POCONOS to BOSTON I got 24mpg.. on the highway this is a great driver-- city driving here in boston kills mpgs bigtime--i'm talking 12-15 mpg..
  • paulo6paulo6 Posts: 94
    Was this based on the trip computer readouts or your own calculations?
  • sweendogysweendogy Left lanePosts: 1,299
    own calculations - i did use the computer to calculate the avg speed.
  • paulo6paulo6 Posts: 94
    Do you know how well your own mpg calculations correlate to the trip computer calculations? Wondering how accurate the trip computer calculations are.
  • sweendogysweendogy Left lanePosts: 1,299
    the MPGS on the car computer are pretty close usually within .4 mpgs.. The only wish is the gas gauge would give a more accurate miles left on tank--i recently had the warning light go off --after driving another 20 miles -I filled up-- and was able to fill over 18 gallons of gas --so another 40-45 miles of highway driving.. This was not the first time. I think the warning light triggers with less then 4 gallons left inthe tank.. --ITs also pretty scary seeing "*****" on your nav screen--
  • paulo6paulo6 Posts: 94
    I know the last 30-40 miles TO GO disapear within 10 miles (or even less) usually and I get the scary ******. My car (08 G35Xs) has just over 3K on it and I struggle to get 17MPG on combined driving (mainly city). I still struggle to get to 20 when I am on HWY though. I am blaming cold weather and NEW car factor...will see what happens in summer. This triggered my Question regarding accuracy of trip computer.
This discussion has been closed.