Near the 2k mile mark....I'm not breaking 20mpg
 

I even just went on a 200mi freeway trip this past week!!! Not driving fast either (75-80mph)..only one spurt of probably less than a mile down hill saw an indicated 120..then backed off...I got 19.2.....I'm kinda stunned. Is it not broken in yet?

Auto?

yeah...75-80 is pretty fast considering most cities speed limits are 55-65...higher speeds for those of you out in the boonies, 19.2 sounds normal

try goin 60-65, you'll see a pretty big difference

I avg 26 hwy going 75-80, maybe it's the altitude?

i have 14,400 miles and since the first day i drove it off the lot, i have averaged 19.1...if i were you, i just wouldn't worry about the gas mileage so much. i'm sure you did your research before buying this car, and on every review it says the disadvantage of owning this car is the gas mileage....so i hope you weren't expecting really high mpg...

I've averaged as high as 25 mpg on purely highway (65 mph) with a/t, usually it's more like 20-22 or so (80 mph),

you can tell how to drive in gas saving mode by that digital mpg meter in the dash, sometimes letting of gas a little when coasting helps a bit, it depends on how you modulate the gas pedal

but most cases it's too difficult to maintain a high mpg, car is fun to drive

you lose about 1mpg for every 5 mph over 60

Yeah, my car is an auto. This really is my FIRST Luxury Japanese Import Car. I've been a Bimmer driver for at least a decade and Just turned in my 530i going 84-85 mph on long stretch of road averaging 26.4 mpg/68mph average on computer on my last road trip from SF to LA and back...and sometimes higher speeds. I'm not worried about the mileage per say, just...well...because the reputation of Japanese cars being fuel efficient!

I like the car and it's value, trust me...and the money I save in the Lease and such more than makes up for the gas...though I'm just under the impression of "efficient" Japanese products! I have also switch over to a Japanese "hunting" truck and found my gas mileage to be higher than my American trucks (Now have an old Montero -vs- my fullsize Bronco before).

I do like driving this car, just felt a bit.....misconceived.

in the G35 case, efficient means lots of power from a v6

I just came back from a little road trip and averaged 27.2 mpg at 73 with the a/c off. Coming back was a little warmer so i had the a/c on and it dropped down to about 23.5 at the same speed. I left with 3k on the clock and came back with 4100. Before i left i was getting 15 mpg in the city and now im getting 17.8-18.3 in the city.

My mpg reads 19.2/gal. which is a lil better than what I was getting from my V8 SUV I used to roll in. I know our cars have such bad gas mileage, but who cares?! This VQ motor was not built for fuel efficiency. What do you expect from a 3.5L engine pullin' over 300 hp?!

I say.. just put your pedal to the metal and enjoy the ride~!

I'm at 4k miles and the ecu says I'm getting an average of 22.5mpg in my X. My last tank was 24.81 all hwy at 74mph.

But, like others have said in hundreds of threads like this one, enjoy the car and don't worry about the mileage.

Also remember that the epa estimate for hwy mpg is determined by driving the car on a closed loop at a constant 48mph in top gear, no slowing down or accelerating, with the A/C off... there's really no way to even come close to their number in real-world driving.

Not true!

Wind resistance varies exponentially with speed. You may loose 1 mpg from 60-65. However, you will be loosing A LOT more than that from 119-120 mph as the original poster indicated he did.

{F}_d= -{1 \2} * rho * v^2 *A * C_d * {v}

The Drag equation calculates the force experienced by an object moving through a fluid at relatively large velocity (i.e. high Reynolds number, ), also called quadratic drag. The equation is attributed to Lord Rayleigh, who originally used in place of (L being some length). The force on a moving object due to a fluid is:
see derivation
where
is the force of drag,
is the density of the fluid (Note that for the Earth's atmosphere, the density can be found using the barometric formula. It is 1.293 kg/m3 at 0 °C and 1 atmosphere.),
v is the speed of the object relative to the fluid,
is the reference area,
is the drag coefficient (a dimensionless constant, e.g. 0.25 to 0.45 for a car), and
is the unit vector indicating the direction of the velocity (the negative sign indicating the drag is opposite to that of velocity).
The reference area A is related to, but not exactly equal to, the area of the projection of the object on a plane perpendicular to the direction of motion (i.e., cross sectional area). Sometimes different reference areas are given for the same object in which case a drag coefficient corresponding to each of these different areas must be given. The reference for a wing would be the plane area rather than the frontal area.
http://en.wikipedia.org/wiki/Air_resistance

Not anymore. With the 2008 model year standards, they now test actual city driving, highway driving, high speed, air conditioning and cold temperature. The tests are also supposedly done on a dyno with a driver going through a simulator that simulates "real world" situations.

My last highway trip I averaged 25mpg running about 80mph the whole way. My best city only tank was 19 driving like a grandma. My average city tank is 16 or so. Combo highway/city driving I'm usually around 18 or 19.

I've consistently had these kinds of mileages since I bought the car.