Auston71

Hey guys, I'm new to Lexus, only had mine for about a month so far and really enjoying it! Anyways, I was curious if anyone knows how the average mpg is calculated in the computer? Like the date range that they use to calculate it? Btw I have an 06 IS350. I've only owned Dodge products and on their systems you can reset it whenever and that's how you know that date range of the calculation but didn't know if the Lexus is a date range or a certain number of tanks or if anyone knows? Not too important, I'm not a huge MPG guy, hence all the Dodge products, but was going through my display screens and was curious! Let me know if anyone knows the answer! If this is a repost, I am sorry! I couldn't find a thread that gave the answer so here I am. Thanks again guys.

tex2670

There's 2 measures -- average and tank average. "Tank avg" resets every fill up. "Average" resets when you manually reset it (or if the battery got disconnected, etc).

BTW--you probably want to pose questions like this in the 2nd Gen IS Forum, not Car Chat.

Auston71

Oh okay great thank you! Didn't know you could reset it. Okay, sorry I didn't see that in my phone otherwise I would have. Note for next time! Thanks!

swfla

iTrader: (1)

Be advised that the onboard calculation can be off by several MPG. Most accurate is to fill the tank, record the odometer, drive until the tank is below 1/4, refill and use a calculator by dividing gallons used into total miles driven.
Even though others have posted accurate systems, it's smart to check it long hand so you know if yours is accurate as well.

mmarshall

Welcome to CL, Auston71

My experience in several vehicles that the trip-calculator mileage is usually good to within 1 MPG...and sometimes right on. You will see the wildest swings....and the greatest variation.....right after you fill up and drive away (assuming that you have reset all the old functions correctly). Then, as more miles accumulate since the fill-up, the average fuel-consumption rate will gradually stabilize, though you will still notice big momentary variations as you accelerate or back off on the throttle and cruise.

Evitzee

I've found the mpg calculation pretty accurate on Lexus', certainly within 1 mpg. There are various factors that can affect your actual mileage calculation: accuracy of the odometer ( Mine is about 2% low so actual miles driven is 2% more than the odometer) and accuracy of the fuel dispensed, and this can vary due to calibration at each pump and temperature of the fuel in the underground storage tank.