May be a stupid question

[jmespo]

OK, I know this is stupid, but I just came back from filling up the car and I was wondering. The indicator was on the last square, and from what I have read on this site that should mean I have about 2-2.5 gallons left. I started to fill the tank and it clicked off at 9 gallons. Since I was close to a whole $, I decided to "top it off" Well I was able to get another gallon and a half in. I know that you should not top off the tank too much, but what is too much on this car? Also, my display said I was getting 41.5 mpg, but when I did the math with 10.5 gallons, it dropped to 38 mpg

I did try to find something about this in the KB, but may not have asked the right question.

Thanks in advance

[Tideland Prius]

it truly fluctuates. If you calculated lower than the MFD, you probably pumped in more than the last tank. Average it out over a few tanks and see if the two numbers come closer.

[oly_57mpg]

I'm beginning to believe that MOST, if not all, pumps cut off too early when they are used to fill a Prius.

I've used many fuel pumps through out the Puget Sound, and I can always get at least another gallon of fuel in the car before I get close to topping it off.

Some have suggested holding the pump upside down whilst filling the car.

[wb9tyj]

when the pump clicks off, im good for 1 more gallon(us)...anymore tends to bubble it out...of course in the summer you can get more in due to bladder expansion...

[priusham]

Oly, I'm not so sure... I believe that fuel pumps shut off early on all cars.

I typically squeeze in 1/3 to 1/2 gallon more and have never had a backsplash.

In my log, I track both how much fuel was pumped in when the pump stopped automatically, as well as the actual amount of fuel I squeezed in.

See for yourself and compare...

http://www.w8kc.com/priusmileage.htm

[galaxee]

After a few fillups, I have just started putting in 10 gallons when I hit the last bar. Sometimes I'm sure I could put in a whole lot more, but I always stop at 10.

And half the time the pump stops around 9.5 so I have to put a few more clicks in.

[Presto]

The past cars I have driven and the Prius, click off automatically. I usually slow fill about 4 more litres (1 gallon) or 5 litres more to get it to the very top. Just have to be careful when you top-off in the Prius. Overfilling means gas will spray out when the pump is pulled.

Also, I have found that if you want every penny of gas to come out of the nozzle, you can rotate it 90 degrees so any remaning gas in the nozzle comes out.

[ltu1542hvy]

I usually set the pump on its lowest setting and then give it one more good squeeze and leave it at that. Unlike out west or in some desert areas gas stations around here are plentiful, so I really don't see the point in maximizing range, in particular in light of the inconvenience and danger of a "splashback" in filling up, or the hassle of worrying about running out of gas on the other end. When the gauge is down to one bar I start looking for a gas station, and only once out of maybe 15 fill-ups have I let it get to the point where the last bar started flashing. I usually get 400 - 460 miles between fill-ups, which usually are 9.5 to 10.5 gallons each for me, and I'm perfectly happy with that.

I also concur that you need to keep track of at least 5 or 6 consecutive fill-ups to get a true picture of your mileage. Some of my tankfuls are 2-3 mpg lower than indicated and a few are 2-3 mpg higher. I have been using the Total Car Palm Pilot program that you can download here on PriusChat to keep track of my calculated mileage.

[plusaf]

topped off cutoff
10.006 9.38
10.004 9.38
10.659 9.49
10.534 8.527
10.450 9.565
9.120 8.8
5.957 4.9
9.602 9.156
9.208 8.363
12.935 11.658
11.716 10.187
9.530 8.648
10.884 9.95
9.492 8.443
12.184 10.931
12.495 11.633
12.739 12.005
9.712 8.72


that's my data for the last 6600 miles or so for my trip.
the first number is the number of gallons i managed to squeeze in, and the second, lower number, is the number of gallons registered when the nozzle first clicked off.

in all of those fill-ups i've never gotten a splash-back. the only time that ever happened to me is when i pulled the nozzle nearly out, to where the end of the nozzle was just inside the rubber ring down in the filler neck, and kept pumping. if you nurse it with the nozzle down in the filler tube, you should average about one more gallon, and it pretty well fills the tank up to the top of the neck.

[DaveinOlyWA]

i fill full speed until about 6-8 gallons then slow down to the lowest speed. let it stop fill to nearest quarter then call it good.

used to cram and ram an extra dollar or two. got tired of wasting my time. the extra 2-3 mins spent to get it in...well what can i say? im worth more than that.

only exception was the last tank. was sooo close to 10 gallons (never had that much before) i ended up clunking in 70 cents after first shutoff because i figured after 600+ miles that i should get at least that much in there.