I'm a "cold weather canuck" and have a 2004 G35X with about 10,000 km on it. I average anywhere from 14 to 17 litres per 100 km (sorry, I have no idea what that is in mpg because I don't know how to convert it!), or 430 to 480 km per tank. This is 99% city driving. I noticed last winter when temperatures were -20 C or lower, the mileage was really bad - about 22-23 litres per 100 km - maybe because I was warming the car up for about 10 minutes before driving. I bought the car new and did not notice any improvement in mileage after it was broken in.

 

'05 Sedan 5AT with 5,000 km running on 91 octane:

During 100% city driving I typically use 13.5 l/100km = 20.9mpg(Imp.) = 17.4mpg(U.S.).
My only highway trip so far used 9.2 l/100km = 30.7 mpg(Imp.) = 25.5 mpg(U.S.) at 110 kmh or ~68 mph.

Considering it's rated for something like 22 city/33 hwy. (Imp.), I'm really not disappointed so far.

 

Car: 2003 sedan auto

City ranges from 17-19mpg depending on how hard I run it. The worst I've ever gotten was 17.1 and that was beating on it pretty good. I leave the car in "4" around town and see better MPGs than just leaving it in auto.

Highway 24mpg at a steady 78mph with three passengers and a very stiff 20mph+ High Plains cross wind. That's the only 100% highway tank I've ever burned through. I think the car is capable of 25-26mpg a slower speed and with less wind.

Average 20mpg. >80% city and <20% highway

Octane 92. The highest I can get in Kansas/Missouri

 

On the Saturday after Turkey day I drove from Saratoga NY to Long Island NY.

Distance = 215 miles
Traffic kept moving...no real bad traffic jams, speed was in the 65 to 80MPH range depending on terrain ie; fast down hill and I let it slow a bit going up hill.

Gas=Sunoco 93

According to my Nav display my MPG was 25.2 this is in my 2XX5 G35X with about 10,000 miles.

 

My long term average is just under 23 MPG with 57K on a 2003.5 6MT sedan. I do use the 91 octave from either Arco or Chevron, which ever is cheaper. When I spend a lot of time in traffic, it gets down to 21 and on the highway upwards of 25.

 

Damn...are you saying you can't hit 300 miles before the light comes on!?....time to ease off the accelerator!

I average 21-22 (90% highway driving)...my best MPG (99% highway) was 26.49 MPG (I couldn't believe it either).....all highway w/ cruise control set at 65 MPH...that was using 87 octane too. I have a RWD 5AT sedan and have now committed to using 91 octane from now on.

 

If I do nearly all city driving, I often see the fuel light come on before 300 miles too. When the fuel light comes on, I know I have used about 16.5 gallons.

 

'04 AT - 15K miles... 91 oct. avg 17-18mpg (combo city/hwy) in So Cal Hwy is like most city though.

Usually 320 miles per tank.