Computer DTE calulation doesn't match MPG?
 

Just got a (second) 2012 RX350. 13,000 miles. The Distance to Empty is confusing me. Doesn't come close to matching the tank size times either the mpg since last fill-up, or the overall average mpg. Overall mpg is 17.x. mpg since last fill-up varies from 17-21. But when I fill the tank, the DTE says maybe 260. With a 20gal tank the DTE after a fill-up should be in the 340-350 range.

This isn't happening on our other 2012 RX350 with about the same number of miles.

The needle gas gauge appears to be right, based on where the needle is before a fill-up and the number of gallons purchased.

????????????

My 13' RX and '14 IS behave similarly. The DTE is very conservative to ensure you don't run out of gas by you filling before you're really empty.

When DTE hits zero, you still have about 10 liters (2.7 gallons) of fuel in the tank.

Thank you
 

ahhhhhhhh, that would certainly explain it. With the gas gauge showing half I put almost exactly 10gal in the tank, meaning approx 10 was still in the tank. DTE should have shown 170 prior to the fill-up, but was far under that. After subtracting 2.7gal if DTE was using 7.3gal as the remaining fuel, then it would register 124 miles. I vaguely remember it being somewhere in that vicinity, which at the time made no sense.

Thank you VERY much. I'm going to check my wife's 2012 RX350 and see how that registers. I hope they are both equally conservative. Otherwise it will be confusing :)

You're welcome. My previous two RXs also behaved similarly so it's a common consistent function. :thumbup:

I double checked my other (wife's) 2012 RX350. It too had a conservative DTE calculation, but not as conservative as mine. On my car I extrapolated that DTE would hit zero with 2+ gallons left. It was probably 1 gallon on her car. Thanks again for clearing up the mystery.

Half on the gas gauge doesn't translate to half of the tank.
I know, it's confusing.

With the needle on half, i usually get 13-14 gallons in up to the first click on the pump

Gas gauges are no where near accurate. If our vehicles ran out of fuel when the gauge says empty we would all be in a mess. Even the "miles till empty" is way conservative.

It is all ment to only be used as a "guide"

I wonder about this. I think the display calculations are based on averaging each minute of gas mileage from the fuel economy detail screen. If the car is sitting still, and the engine is off, running on hybrid battery power, that minute shows zero mpg. I think that throws off the average. The instrument panel calculations seem to be from a different data source.

i have a 13 350, full tank has been showing 275-285...