508 miles till empty? what?

From what I have been reading from other members is that your "lifetime" mpg's are used to calculate the tank to empty.

 

Does that imply that the car stores a "lifetime mpg" somewhere?

 

The 3rd generation Prius seems to remembers your overall FE but I've notice the range is also slightly affected by the current tank's fuel efficiency as well. When the Prius gets 70-80 mpg per trip - the Prius' range for that tank of gas will incrementally increase ever so slightly after each trip. The Prius' range and fuel efficiency is lower for the winter than in the summer. With warmer weather, the Prius fuel efficiency and range increases. On my last fillup, I was able to squeeze 680 miles from 10.11 gallons of gas. The most I've travelled on one tank of gas sofar is 727 miles using 10.25 gallons. I'm using 10% ethanol 87 octane gas (which has less energy than 100% gas) but my fuel efficiency and range is a higher because I'm hypermiling in a metro environment at mainly low speeds.

 

DC or Baltimore? I used to live in Harford County.

 

My driving environment: NW-DC, Montgomery County, Prince George's County, and Fairfax County. Traffic jams are common especially during rush hour. By low speed, I meant my estimated my average speed to be about 17mpg. To compute my MPG -I divide odometer Trip A by the gallons of gas needed at each fillup (I stop at the gasoline pump's first click-auto shut off) to compute my mileage. After each fillup, I reset the odometer Trip A to zero. I also reset both of my ScangaugeII after each fillup. My ScangaugeII AVG gives a FE estimation per trip. The Prius MFD for the odometer Trip A provides a (running) const. MPG -- a FE estimation per tank. WHEN there's a low fuel warning beep and the fuel gauge's bottom bar starts to blink THEN there is about 1.6 gallons of gas left in your tank and the range remaining is about 30 miles. When the range initially drops to 0 miles, the 2010 Prius has almost 1 gallon of gas left in the fuel tank (scanguageII xgauge Flv=.9)

 

I don't usually watch my 'distance to empty' very close. But over the weekend, crossing Steven's Pass twice on my 2012's first low tank test, it was very strongly affected by short term fuel consumption as I climbed and descended, 4000 vertical feet on this side and 3000 on the other.

To illustrate, this hiking outing started with DTE = 221 miles and TripA = 0 miles, with an expected day's trip just under 200 miles. Burning fuel furiously while climbing the pass the first time, the DTE+TripA sum shrank to 197 miles, then increased to about 210 on the descent. Climbing the second time, the sum shrank again, to 183 miles, then again started increasing part way down. Curiously, the increase did not start immediately on the descent, still shrinking for several miles while we burned no fuel during B-mode braking. Only after some time was the car convinced that it would no longer be burning fuel furiously in climbing mode. DTE never increased on the downhill, but only slowed its decrease, always decrementing at least 1 mile for every 2 miles driven. DTE finally reached 0 miles when TripA was 198.

While I wanted to push the car all the way home without refueling (now 215 miles due to a side trip), JimboPalmer's advice took over -- refuel 1 bar earlier if the spouse is in the car. One added (overpriced) gallon took about ten minutes to fully register on the fuel gauge (the blinking pip turned steady, then 2nd pip reappeared), but DTE (registering 4 miles at the moment the gallon was added) continued to drop to 0 miles at the 1-for-2 rate mentioned above.

Bob Wilson's tests three years ago, actually running the tank to fuel starvation multiple times, found more fuel than that. Though not all cars in all conditions may find as much.

My ScanGauge FLV's virtual zero point is not the same as the actual bottom of the tank, but seems to be a bit above the bottom, at least on the (now sold) 2010. And I say 'virtual' because FLV doesn't actually go down to zero, but froze at 0.7 gallon. My 2012 hasn't yet been pushed that far.

 

When I first fill up, my DTE is about 590 miles. Typically when it hits zero, I have driven about 550 miles. I typically don't refuel until about 600 miles and usually have about 1 gallon left.

#DateMilesGal.MPGPriceCity %Notes​

​

Date Mi. Gal MPG​

6/3/12 596.0 10.84 55.0 ​

5/26/12 599.0 10.68 56.1 ​

5/15/12 597.0 10.77 55.4 ​

5/8/12 563.0 10.27 54.8 ​

So, since I use about 1 gallon after the zero and I have 1 gallon left, that means there are about 2 gallons left when the DTE hits zero.

Note: the above cut and paste may not show as it should ... I fixed it.