First Tank of Gas, What a Ride !

Oh no! I'm so afraid of the same thing happening to me (I notice we got our cars the same day!). I just hit two bars today, and I think I'm gonna fill up tomorrow just out of paranoia. This is totally foreign behavior to me...I've always been one of those people that pushes it to the limit with the warning light on. But with the horror stories of the "guess gage" here and on other forums, I don't think I'll chance it!

 

It varies by the car. I've gone 134 miles on the blinking bar. I was showing over 59 MPG at the time. I seam to be able to safely go about two times the mileage that I'm getting, which means a hundred miles is seldom a problem.

My strategy is to fill it all the way up and then when I've gone 11 times the current average MPG, I think about filling up. Games like this have replaced racing to pass all the cars that are ahead of me on the road.

 

Yeah, I too have been very happy with my first tank. We were down to 2 bars and decided to fill up just to check the mileage against the display. Went 375 miles on 8.5 gallons. That figured out to be 44.1 mpg. The display showed we were averaging 43.8, so pretty close. Filled up slowly, as we had seen suggested here. When it clicked off at 8.5, I was skeptical. Tried to put a little more in, but it almost immediately stopped again. Full! What makes this even sweeter is that we would have only averaged probably 21 with the PT Cruiser we got rid of to get the Prius. Loving it all the more!!

 

LOL - I got mine on the 24th and filled up twice when I got to the 1/2 tank mark...... I am such a chicken!!

 

Got 600 miles on this last tank. Last pip started blinking at 580 or so. MFD showed 60-61 MPG. Filled with 10.55 gallons. Pump clicked off at 9.33, and I usually add an extra gallon after that.

Twice the display huh? Means I might have gotten close to 700 miles on this tank?

 

Ya know, the warm-weather folks are an inspiration here! 600, 700 mile tanks? When will summer EVER return? It's been spring like in the 50s or so here but not quite the summer temps of 80s and MPGs in the 55s. After running out of gas with 70 miles on the blinking bar at 40 degrees, I've come to realize the warmer temps last summer (80s) allowed me 75 miles on the blinking bar and a 10.9 gallon fillup, meaning I had roughly 50 more miles before the gas would run out. Now I know. And that's half the battle sometimes. I agree with Ray, playing the gas "guess"-gauge is alot more fun than trying to speed around people and generally wasting gas...

 

Dan-

You had a 700 mile tank on the line and you let it get away. With 61 MPG on the display and if you filled it up until you see fuel in the neck of the filler tube, you can get the elusive 800 mile tank.

This is, of couirse, just for amusement. I'm really glad to see the high numbers out there. You know what it takes and all the subtle things that can help and hurt your effort. I don't do anything to delay other drivers and I just drive it right around the speed limit unless I'm approaching a light or the top of a long down hill run. Are you using neutral much?

By the way, I was a little skeptical about just how much benefit there was to be gained in high humidity condtions, but I now am convinced that my highway miles definitely show a noticable improvement in high dewpoint conditions. Kudos to you.

 

Weather was quite mild this past week and tank, so I didn't need the AC much. Avg temp was in the low 70's, and humidity was low. Often ran with windows open at least a bit. Speeds about 45-55MPH on US19, a major 4-6 lane highway with traffic lights.

I am doubtful I'll ever see 800 miles on a tank, it is hard to maintain 60MPG and hard to get to use that 11th gallon. I've only exceeded 11 gallons twice, and at least once I put in a gallon or two beforehand. It did dip down to 59, maybe 58 midtank, but that could have been the previous tank.

Anyone notice that the first trip or two after filling up gives great mileaga? Why is that?

 

If you pull away from the pump before the reset then your first accelleration is free. Is that it?

 

You'd think so. First off, I usually find it resets right away if I forget. It has time to settle to full while I write down my trip B (verify tank mileage to tenth), write down tank fill, write down MFD MPG, calculate actual MPG. THEN I drive away.

Ususually first mile or two has very low MPG but rises and settles quickly to high value. I once got home showing 70MPG! Was only a few miles though, and quickly lost that the next day.

 

Its probably because the car is already warmed up. Everyone has noticed that the first 5 minutes ussually only gets 25 MPG, and if your at the gas station, the engine's already warm, and your getting the higher mileage. That is, unless you fill up within the first few blocks of start up.

 

That would be true for the first trip home from the station, but the next trip the next day is higher too! Then it starts coming down.

 

Maybe your practice of filling the extra gallon has some effect.
Like the tank gage doesn't recognize REALLY full vs. full.
Or maybe the really full tank has a higher fuel pressure.
I don't know the specifics of how the air bladder works, but I don't add that extra gallon and I've never noticed any different mileage after a fill, except for that accounted for by engine temp.

 

Spilling one drop of gas while topping off your tank will create more pollution than your prius will create burning the entire tank. Even if you don't spill while at the pump, fuel splashing around while driving can still cause spillage and defeat the evaporative emissions controls as it becomes saturated with liquid fuel.

Why undue all the environmental benefits of the prius in just one second? Spilled fuel gives you ZERO mpg and is 100% hydrocarbon pollution, to say nothing about the hazardous runoff it creates.

My Prius gives me far more range than any other car I've ever had. Even if I only get 10 gallons in, I still won't be visiting the gas station for almost a month. Heck, I even fill up in the suburbs when I'm out there, since gas is about 20cents cheaper outside of Chicago/Cook County.

Say NO! to topping off!!!

 

gschoen-
How do you know that fuel sloshing around will saturate the carbon canister? Do you have any proof of this or only supposition? Where did you get the info about one drop of evaporated gas equalling a tanks worth of emissions in the Prius? It is my understanding that the Prius emits 2 ounces of toxic emissions plus 230 pounds of carbon dioxide per tank. I have been told that topping off will hurt my mileage. I just filled up after 654 miles at 56.9 MPG so I doubt there was any validity to that off the cuff warning.

If you make statements without any basis in fact, please let people know that you are simply guessing.

 

Well, I think it's fair to say that spilling ANY gasoline on the ground while filling will exceed the amount of unburned hydrocarbons that would be emitted otherwise, because the normal emissions are zero. That's one of the primary reasons NOT to top off the tank.

There's no way to get around the burned hydrocarbon emissions since you are going to burn them eventually.

The "sloshing around" is probably a non-issue.

 

I have a question. I generally fill up at one or two bars at a gas station about 2 miles from my home. The care is fully warmed up and I just fill to the click off. I then get 70 -80 m.p.g. home then my milage plummets to the mid to high 40's the next morning when I go to town or work. I then slowly play catch up for the rest of the tank with my m.p.g. rising now to the low 50's. The last 3 tanks the car MFD average was 2-3 mpg below the calculated mpg. Is this normal behavior? Temps are in the low 50s and high 40's. Thankfully normal for this time of year and raining. Over all the pattern of low slowly rising to the high on the computer over the tank holds. Do other people see this pattern?

 

Hdrygas's experience is close to mine, except not quite as drastic.

I think the reason I had stellar MPG at the first few trips last tank was probably because winds were favorable. Yesterday they were not as favorable and MPG was close to 50, even when doing 45.