17-19 mpg on a 2015 IS350 AWD in Bay Area traffic, it's pretty bad.
I also noticed CA Costco gas gives me lower mpg vs. MA/CT Costco gas...:uh: confirmed on the hwy.

I'm pretty much getting the exact results as you.

I have a 2016 IS350 FSPORT and I get 16.9 with city driving, 18.3 with mixed, and 24 with mostly highway driving without much traffic. I have never come close to the EPA 27 MPG mark.

Got an update on my 88k mi IS350 now that I've paid closer attention.

50% City / 50% slow country roads - Can accomplish 19 mpg without causing any major traffic jams (half tank of gas for the study)
Typically I get 18 mpg but been as low as 16.

100% Hwy - 26.5 mpg over the course of 230 miles.

Half of this trip was very aggressively. WOT several times and ++85mph the nearly the entire time 80% sport mode.
The other half 65-75 mpg (like a normal human).

:yikes: You've either got a pinhole in your tank or your neighbor is siphoning the gas over night.

Whatever it is people will still complain bro, i've owned an AWD IS350 for 3 years now and i always get good MPG with Super Tier gas at SHELL or ESSO. People don't realize cheap gas actually gives bad MPG, i compared my IS350 with 2005 Acura TL 3.2L , 2001 Toyota Solara 3.0L and 2017 Toyoya Rav4 2.4L my IS350 3.5L still get much better MPG. "i drive harsh"

Lmfao i'm getting 17.1 in eco mode pretty much ALL the time and 80% highway commutes

I did a little day trip with some friends yesterday, and with some aggressive driving through the twisties as well as highway driving at 75-80 MPH, I was averaging 24.8 MPG on the first tank and about 23.7 on the second tank (which had more of the twisties :D). This is in my AWD IS 300.

When it comes down to it our cars are just thirsty. Seems IS200t and IS350 get about the same gas mileage in real world. The turbo just injects a bunch of gasola and the V6 just has a big mouth. lol.

It feels good to drive my 40mpg CT especially now that gas is 4.27 a gallon for 91 here =(

93 Octane is $3.75 here in Germany and that's the military price since we get it subsidized, I'm definitely feeling it lol. The Germans are probably paying closer to $7 for premium. OUCH.

I had a 2014 250 and the gas mileage was almost as lousy as it is in the 350. I figured if it’s going to be a gas hog anyway, I might as well take the 50% hp increase.

Ha! I'm only paying $4.22! Lol. But seriously we're paying as much as $4.40 for 91 right now in SD.

I didn't expect any better out of the mpg. on these cars, maybe I should have? My 1.8L Nissan gets 31 mpg mixed. So ~19 mpg on a 3.5L much heavier car with a traditional auto trans...makes sense.

Yeah that torque converter sure saps a lot of power. The highest i've ever paid for 91 was $5.27 or so, this was in Santa Barbara in 2008. I drove an E39 5 series back then.

but yeah still not bad compared to europe!