I notice that the Trip Computer and the Gas light come on when there is still a good 3 gallons of gas left in the tank. Yesterday I filled up for the first time and my trip computer said I had 25 miles left. I put in around 13.9 gallons which leaves about 3 gallons of the 17.1 total in the tank. This was my first fill up on my 2008 TL which I have been driving around town slowly averaging about 16 to 18 MPG.

How accurate do you guys find your trip computer to be in every day driving on your regular commute?

 

mine has been pretty accurate..I always fill up the tank for 10 gallons at a time once the low gas sign is turned on, and I can go for in average 190 miles...the TRIP always says 19 MPG (combination of local and freeway)...most of the time I don't want to race or floor the pedal, in order to try to beat 190 miles..


ON A DIFFERENT NOTE:
Last time, I resetted the TRIP just right before getting to the freeway, and unbeliveably I got 36 MPG for about 7 miles of driving with about 50-55 MPH...I thought something was wrong with it...but as soon as I exitted, it went back to 27, then 22, then now 19 AGAIN

 

MustBeTL - you are exactly correct.

The TC will say 0 miles to go with ~3 gallons left in the tank. Or, conversely, when the "Low Fuel" warning comes on, you can drive ~75 - 100 miles before running out of gas.

This has been documented over and over. It is normal. There is a detailed thread in the 3G Garage with milage and fill up data, as well as MANY threads on the question.

Why is it like that?

 

I just posted a new thread similar to your question. My computer is telling me that I am getting 27 MPG?! I would love it but it cannot be true.

 

27 mpg? i want that! mine pretty much always says something ~20 mpg but i know for sure im getting more. o well fuk it. when miles to empty says 0, just fill'er up. done.

 

fill the tank and write down the mileage- drive to next refill- record finish miles and gas used
divide miles by actual gas used- that is your real MPG

 

you could probably go another 70 miles on 0 miles left on the trip.

 

Yeah, I haven't done that but intend to. It just drives me nuts to be told that the computer is working correctly. I should add that I own a 2007 TL and it always has registered between 26 and 27 MPG regardless of how long I go between resets of the system.

 

Yes it is slightly inaccurate to protect cars from careless owners, or absent minded owners.

 

What is real wacky is that if you jump on the highway and cruise at about 75MPH, the MGP will read 30MPG all day long which is sweet.

I don't get why the calculations don't change more frequently since it seems like a little bit of city driving will throw off the MPG and it will never get better, even if you drive on the high way for a long time.