I recently took a 1000 highway mile trip averaging speed of about 75 MPH on cruise control, and the trip meter indicated ave MPG of 24-26 depending on hills, curves, wind, etc. On a full tank of 93 octane, light load without AC and 36 psi on my tires, I could only get about 360 miles, with one pit stop.

It holds 19 gallons. 24 MPG x 19 should be 456 miles on a tank. 26 MPG x 19 =494. I don't even come close. Any feedback is apprecated.

 

You really cannot get all the fuel out of the system to use. When you stopped for gas, you were putting in about 16 gallons, correct? About the max I ever remember putting in my 2004 RX330.

Fuel light comes on very early. Trip meter will say your Distance to Empty (DTE) is nearing zero. The computer's estimate of MPG is somewhat optimistic, IMHO. Did you try calculating by hand your MPG using actual mileage and actual fuel added?

I have made a number of long distance trips in my RX and on several occasions have entered into the range of 425+ actual miles on a tank of gas. Rare, but possible. Still had mileage according to the DTE on the display but did not push it. Best MPG I have seen was just north of 28 MPG on the original Michelin tires and before E10 gas was out in all areas.

 

i get around 330 miles with 40% city 60% highway with a full tank. I am in Hong Kong but have done the km to miles conversion.

We have octane 96 and octane 98 as options. I use octane 96

 

36psi in the tires? That must be a stiff ride.

 

One of your assumptions is incorrect. You are assuming that the cruising range calculated is for the entire 19 gallons in the tank. It actually calculates a point just after the warning light gets turned on. You will have about two gallons in your tank when it says 0 miles. This will prevent you from going completely empty by trying to drive until it says 0.

 

Man... the MPG calculator in our 350 has never indicated above 22 mpgs, even with primarily highway driving and keeping the speed conservative (under 80).

I suppose the AWD does factor in, but still...

 

Calculation should: Fill up with gas to full tank, zero your Trip A.

When you re-fill gas, capture mileage.

Divide Trip A mileage with gallons of fuel filled. MPG.

Did you do it this way?

 

So 16 gallons * 24 mpg = 384 miles. it's close to be true.
remember SUV sits high, low mpg.

 

Our FWD 350 averaged 24/25 mpg. 91 octane.

Back to OP, calculate number of miles driven and divide that number by the amount of fuel pumped.

miles driven / gal. of fuel purchased = mpg

 

mine goes from 300-330.....according to the trip computer....