Mileage & Distance Till Empty Computer

[jpeshek]

I have a 2007 Avalon Ltd and the computer reading for mileage and distance until empty are useless. Not just a little off, and not erring on the side of caution either. Up to 80 miles off on the distance until empty, and it always says the mpg is better than I'm actually getting, up to 17% off. In addition, neither of these readings AGREE with each other. I have tracked this almost from the beginning, and Toyota is pointing to the statement in the manual that says these readings are just estimates and has no intention of fixing the problem. Anyone else experiencing this???

[jag_man653]

Regarding the remaining miles, our '06 seems to always err on the safe side. I have noticed that the computed mileage is higher than the oldfashioned way.
I don't worry about it.

Ed

[mthedford]

I have an 08 Avalon that replaced a Volvo S60. Volvo has this software down to an ART FORM! It is calculated down to almost fumes (about 1 gallon reserve). It recalculates the instant MPG's every so many hundred's of feet, so if you are accelarating or deaccelerating, it shows what your current MPG's are. Every 1/4 mile, it recalculates the remaining mileage, but doesn't change the display until there is a 5 mile difference. Once it gets down to around 50 miles, it starts adjusting in faster intervals. It is very accurate and it properly adjusts the remaining mileage based on the current driving conditions - such as if fill up and it displays you have 350 miles to go based on the last MPG calculation before stopping and you start out on a hwy trip, the immediate MPG's will adjust from say 19 to 30, and the miles to go will adjust up to, say 450 miles. During that same driving session, if you then exit the freeway and start city driving, it will decrease the miles to go accordingly, then if you get back on the freeway, it will readjust again shortly to increase the miles to go accordingly. Very nice, very accurate, and based on current driving conditions, not based on previous tank of fuel avg, like the Toyota software.

Now the Toyota version, REALLY IS USELESS to the majority of consumers. The same scenareo where the avg MPG's displayed at fill up is 19, then you start out on a hwy trip, the miles to go will show about 290-300 miles, then start to SLOWLY count down, but will never accurately recalculate to the real miles to go when getting higher MPG's on the hwy. On one of my trips, I went 480 miles before I decided to fill up again (based on my own math), but the miles to go started out at 300, stayed in the 280-200 range for a couple of hundred miles, and in the 100-0 range for over 190 miles. When you are open road traveling and really need to know if you can reach that next town to get gas, this information is useless. This car has a 18.5 gallon tank and each time I've filled up when it is close or at 0, I've never put more than 13.5-14.5 gallons in it. That 3-4 gallons left in the tank when it shows 0 makes a very real difference when hwy traveling, determinining where/when to make fuel stops.

[hswaters]

I like to watch the instant mileage on my Sienna but I don't expect it to be too accurate in how many miles I have left. After all they cannot know if your going uphill or into a head wind or whatever. All of which could cause an error in how many mile you have left in the tank.

Still I would like to know what parameters are being used to calculate this instant mileage. I have asked in the Sienna forum to see if anyone knows. I imagine if I could find out what parameters any manufacturer uses it would be good enough as they are probably very close to the same.

[John@CdnRockies]

Echoing Mthodford's experience, we also have an '04 Volvo-XC 70. The computer readings on the Volvo are very accurate while our '06 Avalon are pretty suspect. We always have more fuel on hand than the computer indicates when it comes time to fill-up. I have come to ignore the Avalon's computer readings and wonder whether the average mileage readings are equally suspect.

John

[hswaters]

I wonder if the actual equation for instantaneous mileage is top secret? Surely some one has written it some place. Still I have not been able to find it. I did get some answers in another forum that it is calculated from the pulse width of the fuel injectors the rpm and the speed.