Guy’s thank you so much for explanation and for your time to post reply. I don’t know where all you live with so amazing MPG drive in CITY only, no HW.
I live in Brooklyn and my ride takes me true the 25 local signal lights (AC always On) and I have only yet 700miles maybe that is G35 excuse? BTW my record was today 12.4 MPG I will post my MPG after a couple thousand miles. More suggestions of course are very welcome.

Next time you do that same drive reset your mileage calculator and drive like a grandma, don't accelerate or brake hard, just take it easy and see what the mileage does. If its still giving you in the low teens then there's probably a problem. But if you do get like 17ish then its your right foot causing the 9.8mpg

350miles city, 500 highway - conservative on pedal with a few 7k rpm hits. Mostly keep it under 4k

That seems pretty good.
I average 16-17 mpg in city driving, which would be 320-340 miles/tank. I've had up to 28 mpg on the highway once, but normally it ranges from 22-26. Guess it depends on wind direction and speed, since most highway miles are with cruise at 75.

Seems to have dropped recently a little, but Oklahoma is now adding ethanol to it's gas, hurting mileage some.

Just did a 350 mi round trip b/w SA & Hewitt. Took ~$50 premium gasoline @ ~$4/gal. This came out 28 mpg with my 6MT @ 70 mph Texas speed limit.

PF

I do okay when I behave... I just don't know how to behave that often.

Are you freaking kidding me? Either you're a troll or the heaviest footed G driver I've come across.

Ok...I think I should take mine in to service then.

I average 200 miles per tank around Los Angeles...with almost no freeway driving. All stop and go around the city. My trip pc says about 13, and when I average it out it's the same.

Is it just the fact I rarely go above 40 for any length of time, or should I have it looked at?

13mpg may be correct then if you're heavy footed in slow traffic.

My wife averages 22-23mpg

highend - I'm at the other end of NY State driving around in suburbia mostly...but some downtown (Buffalo and Toronto)...I've found a definite improvement after break in (I have about 8,000 miles on my 08)...

I'm getting around 17.5 mpg in mixed suburban driving...My worst tank ever was 14.1 mpg and my best (roadtrip - 90% highway but at high speeds - 80 mph+) was 23.2 mpg...so extremely close to the rated 17/23 mpg figures...and I drive like a jerk in general.

Will see dealer tomorrow at 8am, but I don’t think its any problem with the car, its possible effect to downgrade MPG when AC is always on?

My wife (who is heavy footed) had my X for two days last week. She averaged 19.7mpg in city driving. 10 miles twice a day on a road thats 55mph with about 12 redlights that seem to always be red. Sounds like a few people need the Nissan Fuel Saving Gas Pedal.

should not be that low... Lowest I had during the first 100miles is like 13ish. I pushed the car hard as well. Now its 17-18 mpg city and like 28-29mpg highway on average.

You carry 900pnds of construction gear in your car? lol