Lower psi is definitely more forgiving but I run 38F/40R in mah daily summers. 32 flat all winter (flex is important with snow tires yes?)

 

It's going to depend on TONS of variables. Way to many to answer with one blanket statement.


All i'll say for the sake of this thread and it's revelance to the G35 community is that for my G35x sedan, wearing stock rims and 215/55/17's, i was able to achieve 75K miles of even wear on my Continental ExtremeContact DSW's by running 32-34PSI of air in the tires.

 

Hey guys! So I ended up getting 19mpg on my trip. On the highway, with cruise going 100kmh or 60mph. Does anyone have any suggestions, im really at a loss now and can't figure this out? I'm going to look for vacuum leaks again and also do an oil change (last one was 3000km ago) and run some seafoam through the oil for 15min or so before it, see if it helps.

 

I strongly recommend NOT going the seafoam route for oil. The oem block has TINY oil channels that clog VERY easily (if your sea-foaming the oil that is.)

As for seafoaming the tank ... /shrug/ use little batches over several tanks. The filter and pump is in the tank and you will have to drop it if you foam to much and clog it.

 

this might sound weird.. does your cruise control work ?

 

You can try cleaning your maf sensor. Also check under your car for any loose splash guard that could create any drag.

 

Hey guys! So I ended up not doing an oil change yet and I won't use any seafoam when I do it now, but I ended up getting some TKO 2000 fuel system cleaner by Kleen flo. It's apparently really good (but strong) stuff and cost a pretty penny. But I put it in the gas tank and just from the first 30-40km's it looks like my mpg's are going up! It's preliminary to know for sure but from the looks of it, compared to usual the needle is dropping a lot less. Maybe I just had some really dirty injectors?

 

19 mpg is reasonable on winter gas blend.

 

what was your improved MPG?


I took a little road trip to another town yesterday and got this:



It was a 30+ mile trip each way with mostly open country highway. This is running about 65-70mph in 6th gear. I don't know how you're getting such terrible mpg's! I have about 117k miles on my car btw, running about 35psi on the tires, a/c on low, windows up, recent dealership oilchange, and I seafoamed the brake booster and gas tank (half a bottle for each--so I used one bottle total).

I'm pretty surprised actually how good my mpg's are sometimes with very conservative driving. My daily driver which is a 03 Camry 2.4L Auto gets 21city/26hway compared to my G which is a 3.5L V6!!!!

I'm a little concerned on how your car is/was maintained, and how your driving habits are. This can make a big difference. I shift gears about 2-2.5k RPM's. not sure if you have an auto or manual.

edit: saw that you have a 03 Auto with only 5 gears. The hwy mpg may be worse for you having only 5gears instead of 6. But you should still be getting 21 or more with conservative driving.

 

Hmm...

Tire sidewall states 44psi max on most tires this size 17-19". 50psi seems excessive, although it may not blow your tire or harm it. Manufacturers will usually put a lower max rating for safety and leaway, so 50psi cold is ok. But on hot long drives, your tire will naturally add 2-5psi, so...

If it works for you, fine. But I also follow manufacture's recommendation as they are the ones who make these things. Doesn't mean that it works for you that it is the smartest thing to do.

Another thing, I ride sportbikes at the racetrack. Race tires also have 44psi max. We run about 32psi on the rear tire because race bikes have so much power and speed that they always recommend lower inflation figures. So 50 is insanely high in that case, and can case premature tire blowout. And we always use brand new tires...


edit: Seafoaming may not necessarily improve your mpg's that much. It can add maybe 2-3mpg's, but each car is different.

To the OP, who does your routine maintenance? You or a shop/dealer?

I've been going to the dealership, although you pay a lot more i.e. $60 for my last oil change. To me it gives me peace of mind that manufacturer standards are used (oil and filter). I do my own oil change and maintenance on my Toyota Camry though since its so easy on that car (I'm somewhat mechanically inclined, but too busy to do both cars' maintenance).

 

I would say im getting around 22-23mpg at the moment but I will have to do more driving before I get a better idea. Im a student and live close to the university so I dont do a ton of driving unless I get out of town but will try to give you guys a better idea when I get a few more miles on it, and the cleaner has not run fully though yet so hopefully it will just keep improving. It just seems like the car is burning better and actually has a little less engine vibration when driving, but it could just be the placebo effect haha. Also my tires are at 35psi all around and I am pretty happy with that, especially with Canadian winters. Do you think there would be any other culprits for poor mpg's? Besides what ive already checked? Also the car was dealer serviced up to 95k km's and was actually resold to the second owner by an infiniti dealership and they had it until they sold it to me at 160k km's and got it serviced by a mechanic (not sure if it was dealer serviced though). Ive done a lot of maintenance on the car and really tried to clean the engine up encase it had bad service but I guess you never know haha. Also im not going to lie, I have definitely floored it a few times but 99% of the time now I drive pretty conservatively (used to own a old m3 and a 02 mustang GT where that was no the case) cause im in the recruitment process for the RCMP (Canadian national police) up here and I cant get any tickets ect lol.

 

Every tire I have had on this care has a 50psi sidewall rating. Usually touring tires have 44psi. To be more clear tho, I'm stating that you should put full sidewall (whatever that may be).

 

I get 20 around town 25 on highway . I dont baby it either. I use 91 octane too. Maybe use a different gas station. I use sunoco or shell and bp. No russian valero crap!

 

good point, ethanol filled **** at $2 a gallon.

 

That looks good, but just letting you know from my experience, when I calculate using actual miles / gallons, I always get a number a little lower than what's on my nav screen, meaning the actual mpg might not be as good as what it shows on your nav screen. Not too far off though. Average 24 to 25 mpg is still very good.