My First Tank Mileage, Quantity, Gauge Questions

Well, I had hoped to at least hit 43 mpg on my first tank of gas, which is the EPA's minimum 'expected range for most drivers' in the city but the real tank mileage turned out to be 39.6 mpg. Kind of disappointing but I'm not surprise since I always fail to get higher mpg in the city then I get on the highway. The EPA's testing is weird. It sure makes Prius looked good though. I'll get my highest mpg when I go on a longer highway trip using the whole tank--maybe next October sometime.

Full tank estimate is around 565 miles. Actual miles driven on this first tank was only 380 miles. But it was pretty much all stop and go city driving too.

IF YOU leave the previous tank histories in the computer (I guess you don't clear either Trip A or Trip B (?) then will a full tank of gas show a more realistic range for the car based on how you drive it???

So here is the thing I need some confirmation on if it makes sense. I hit the last pip showing an estimate remaining range of 51 miles. This last pip started blinking showing 27 miles left. I reached the station for more gas showing 21 miles left.

From solid to flashing the last pip lasted 24 miles. Is that about right. From pip 4 to 3 I got 57 miles estimated; pip 3 to pip 2 I got 60 miles estimated; pip 2 to pip 1 I got 67 miles estimated; and that left 51 miles estimated remaining in the tank. On this tank I kept trying to figure out how to reset things on the Trips A & B; nor did I track the pips down from 10. I'm going to repeat and track more data next time.

I'm really interested more in accurate miles remaing and not gallons remaining. I think more in miles, not gallons. But it sure would have been nice if right next to the fuel gauge pips it gave a little digital readout of gallons at that point.

I need to convert 21 miles into gallons of fule based on my mpg for that tank of gas to come up with something 'close'. That's 39.6 mpg and 21 miles. That comes out to 1.9 gallons that should be left in the tank when I filled. I added 9.5 gallons. 1.9 + 9.5 = 11.4 gallons. So am I really only 0.5 gallons off? That may not be to bad a figure? Can I account for the missing 0.5 gallons somewhere? Geez, I should be using a Trip mileage indicator and not the 'Range Estimate' miileage! Of course the results might work out worse too. But maybe there is still something else to account for that would make a difference--like 0.5 gallons remaining in the fule lines and filter?

Next... I reset both Trip A and Trip B and verified at the station then drove home 2.1 miles. Both Trips show 2.1 mi then Cons. (Consumed?) 42.7 mpg BUT Trip A shows Avg. (Average) 13 mph and Trip B shows Avg. 9 mph. Why the error? Which one is correct? If I looked after 50 miles would this error have disappeared?

Thanks.

BTW, so far I am tending to ignore the Touch Tracer Display--I glance down at the steering wheel to know what I'm pushing. I need to work harder at using the Touch Tracer.

 

Maybe I can get away with adding these questions here... I thought that when I was in Power Mode that that section of the Hybrid System Indicator when reached would be in 'white' (very light blue) like as pictured on page 194? I thought I saw this on the dealer test drive? But so far for me even when I select Power instead of Eco this section display that ugly light almost salmon colored red. And that reminds me. I don't like the color. What the heck went wrong with that?

The other thing I noticed. It looks like if you press the Eco button a second time the green 'Eco' main display near the speedometer readout goes out. I suspect at this point that Eco is still running and this is a feature to darken uneeded icons at night?

Lastly, I remember on my old 2007 Prius the Hybrid Battery status would change to light green when fully charged. I liked doing this on long stretches downhill. Likewise it would turn a light purple if it got down to only one bar. Does the 2010 display change colors the same way?

And perhaps more importantly, if you are going up a long steep climb and the hybrid battery shows only one bar are you suppose to do something different or will the car protect itself? For instance should I really be going up the hill at 45 to avoid some trouble instead of 65?

Thanks.

 

I think you missed my thought. If I just finished driving 380 miles on a tank of gas then wouldn't it be a lot closer bet if after refilling that the next tank will be closer to 380 miles then 565? Get it? I know it doesn't work this way now and would require some redesign. I'm just suggesting that 565 miles on a tank of gas is an impractical estimate that I likely will never but rarely even approach. Far more likely to see 400 mile tanks of gas.

On the other Trip mph average. Are you saying that even though the car is stopped when I reset both trip A & B that the clock was running and since I you can't reset both A & B at the same time it produced the different average speeds which includes stop time? If the car wasn't 'Ready' when I reset would the clock have stopped allowing reset to set the clocks equal on both A & B? I'll have to remember to test this next time I reset the trips.

 

I don't think that is really true unless we are all suppose to be hypermilers. I will look forward to a trip one day where I might be able to stretch a tank out toward 500 miles but for a tank average 400 miles is a more likely figure.

Regardless I'm just disappointed the fuel computer that tracks so much can't use the previous history to post a more realistic tank estimate when you refill.

I've read through the manual section on this and that is what partially generated some of these questions. I have flagged the page so I can read through it again and again.

 

I am enjoying the car and once I settle into the fuel stuff better I may just leave the estimate 'off' until the gauge gets down to two pips or less.

 

It doesn't make any sense to me but that's all right for now. For the fun of it I converted the first two in your table from km and l to miles and gallons and then divided to get miles/gallon. The first, if my conversions were correct is rather fantastic at 83.3 m/g. The second came out 55.9 m/g. I think in my old 2007 Prius the best I ever saw over 3 years was a 51.x m/g.

My whole thing about estimates at this point is that if there is no way I can make an estimate useful then I'll ignore it and never use it.

 

I'm now on my second tank and early today the pips dropped to 9 and throughout the day's driving of around 40 miles or so I witnessed 8, 9, 10, 8, 10, 9, etc. Forget where it is now. I've got a feeling it may be finished with 10 though.

I understand that the gauge is far more accurate and linear then the Gen II. I have heard the fuel sloshing on occasion too. I missed seeing this behavior with the first full tank. The fuel sloshing around may have an odd effect on the fuel probe(s?). A service writer confirmed that the Prius doesn't use the old float type transmitter. I think it does have an effect on the mpg estimate--I saw higher mpg today around 43. I can get use to the behavior too so long as it doesn't happen from 7 pips on down. Maybe when the fuel level in the tank falls enough, even though it still sloshes around it does not hit the top of the tank making the distinct sound nor affect the probe(s?) the same way. Time will tell...

I wonder if different fuel additives will affect the fuel probe(s?) any? Or if the fuel sloshing and banging the top of the tank produces a slight enough pressure change that somehow affects the probe enough to cause a pip fluctuation?

 

I'm getting the hang of it, thanks. I guess what puzzled me was when you turn ECO off to normal (no green ECO light) you still get the ECO icon fill in the HSI. I thought it did this so that late at night you wouldn't have to see the green light all the time by the speedometer. If that is a problem I might switch to Normal. I think Toyota could move the green lights from around the speedometer to inside the HSI screen (not now--on another day and time).

It looks like it would be fun to try pulse and glide again since the HSI really helps see what's going on there.