At about 3,000 miles we are averaging over 22MPG on premium gas. On the road we got 27.7 on the last tank.

 

That's great news.
Do you feel it's due to your driving habits, premium fuel, or both?

 

I'd say more the premium fuel than driving habits. My wife and I both have a heavy foot.

 

After I put on some more miles I'll switch to Premium to compare.
I have a light foot

 

Oh, but corn can be soooo good in some cases. Maybe not in my RX350 (in which I use crappy 87 octane), but in my Nissan GT-R, I get 630hp with 91 octane, 670hp on 100 octane, and a whopping 710hp on E85 ethanol. I swear, using corn ethanol is like being on crack. So addicting. True, I do get 30% less fuel efficiency on corn, but the car is so fast on it I don't really care. Burns much cleaner too. Maybe I should convert my RX to E85. That would be an interesting experiment.

 

I seriously doubt the premium fuel contributed much to that. The gas mileage is a selling point manufacturers like to brag about. If using premium gas would increase the gas mileage Lexus would have claim the higher number and not change the recommended fuel to 87 in the 2013 rx 350.

 

My 2013 RX350 (7500 miles) is getting about 23.5 mpg on the interstate, at around 75mph, using regular gas with up to 10% ethanol. Local driving has too many variables to evaluate.
On a related note, I have run the tank down to the low fuel warning twice. Both times it only took a little over 16 gallons of gas. Does that sound right?

 

Yep, sounds about right. Have never put 16 gallons in my RX yet and I have run the cruising range number down to single digits. There is a great deal of tolerance built into the system as a safety measure. Don't want you running out of gas because you did not see the light come on right away.

 

2014 RX350, ran till the warning light. Gas gauge showed one tick from empty. Fill was 16.2 gal. Dash showed 30 miles remaining. Avg on tank was 24.5 MPG. 80% highway. First fuel up on vehicle.

Since the gas tank holds 19.2 gallons, there were 3 gallons remaining when the warning light lit. I should have been able to drive another 60-70 miles at the current MGP rate. The fuel gauge showed one tick remaining which would equate to around 2-3 gallons.

 

My 2012 RX 350 has had steady improvement in MPG! I now have 6700 miles and we went to N.C. from Western New York averaging 23.9 MPG. 87 grade gas!
Never expected to get above 22 MPG so I am very happy!

 

Approximately 18K miles on it.

I just drove From North Georgia to Tampa

Average just shy of 26mpg's. What's strange the mpg's start to decline once I hit Florida; always does.

about normal for me??

 

RX350 Entries at fueleconomy.gov

 

I have a 2010 w 60k,. City is 20mph qand highway is 23 at 75-80 mph.

 

i do mostly freeway with the RX 350.
( my city car is the RAV4 EV)
anyway here are my latest numbers

at 720 miles the 2013 gives an impressive 26mpg ( regular unleaded fuel)
my 2011 RX 350 with 21,000 plus mies averages 25mpg ( premium and regular unleaded)

 

Wow, amazing numbers. I'm getting 16.6MPG after 10k miles in my F Sport. 75% local 25% freeway though. Wish they would release the F Sport Hybrid over here.