Eddo

Does anyone know how the Lexus computer calculates cruising range immediately after filling the tank with gas?

triplecore

yes it does. Because after you refill it the Cruise Range is not available till like 30 seconds of driving.

jfelbab

It appears that it is calculated on your recent MPG. When I'm on the freeway and averaging 25-27 mpg it gives me a driving range of over 400 miles. When in the city and my avg mpg is 22-24 I'm down around 385 miles.

triplecore

Thats weird maybe they changed or updated in later years. I have a 04 RX and the computer after a full refill always read 311 miles. I have never gotten more than that.

jfelbab

My RX is an 04 AWD. Did you mean to type 411 miles? I don't ever recall seeing a range as low as 311 miles. Or are you doing most of your driving in San Francisco? LOL. What kind of mileage are you averaging?

AM1

iTrader: (6)

311? thats a lot. the most i have ever gotten is 265 or so from a full tank.

triplecore

MASS were pretty much flat. Alot of local driving and twisty old pot holed roads. I spent sometime in SF. Why would you drive they have a great public trans system. I think it was called Muni or Munee. The monthly passes are a bit expensive + the buses hold all types of people its quite entertaining lol.

How do you get 411 miles on your? Fill me into your secret. I use premium unleaded from Mobile, but sometimes Shell

jfelbab

I haven't any secret. I usually use Shell Premium. Actually any Top Tier supplier will do. - http://www.toptiergas.com/retailers.html

I get between 385 and 420 miles in my range after a fill-up. I assume it calculated this range based on the last average MPG calculated by the computer. I assume this because when I drive freeway on long cross country road trips I average 25-27 MPG and when I fill up my range is always just over 400 miles. When I'm in urban settings and my mileage is down in the 23-24 mpg my range is usually around 365-385 miles. I believe there has to be some calculation based on recent mileage being done.

What is your measured mpg for your RX? Does the calculated range estimate accurately represent your real driving range?

Here are my assumptions. This assumption correlates well with my driving experience but is just my guesstimate on how the range is calculated.

The gas tank capacity is 19.2 gallons. The warning light comes on with about 3 gallons remaining. Assuming the calculation subtracts this reserve then you have about 16 gallons of fuel to calculate the range with.

16 gallons @ 23 MPG = 368 mile range
16 gallons @ 24 MPG = 384 mile range
16 gallons @ 25 MPG = 400 mile range
16 gallons @ 26 MPG = 416 mile range

These numbers match up well with my driving experience.

If you look at your case of 311 miles range the computer is assuming you are getting about 19 MPG. (311 miles / 16 gallons = 19.4 MPG) Is this what you are actually seeing?

Or for AM1's 265 mile range. (265 miles / 16 gallons = 16.5 MPG)

The G Man

The cruising range is calculated constantly using your gas tank level and the MPG computer. After the tank is fill, it just use the MPG number you had before the fill up and multiply that by the number of gallons in your tank.

dhamaka127

I get right around what you got...

catdaddylo

Your assessment is spot on with my own observations. I also try to keep a 91 octane balance in the fuel tank jugling between 93 and 89 octane and refilling at the half full mark. I also run 35 PSI in my tires.