The Prius beeps when there is only one bar left in the fuel gauge, then the bar keeps blinking. The electronic gauge doesn't indicate how much fuel is left in the reserve. I like to use some of the reserve that by my calculations is about 2 gallons. If you reset the Trip odometer after topping off the fuel tank a good indicator of when to refuel, and use some of the reserve, is to multiply MPG x 10.
I agree. I wish the car worked that way. The gas tank is 11.9 gallons. It would be nice if it beeped at 10 gallons used or 1.9 left. Your MPG X 10 should equal your trip number if you reset your trip when you fueled up. Example: Trip A shows 550.0 miles, Const MPG should show 55.0 and if it beeped at that point you should get about 104.5 miles until the tank is dry. (1.9*55 MPG = 104.5 miles) Instead it beeps at 9.X miles, I think it is close to 9.5. I also found the tank is not 11.9 gallons. I have put 12.2 gallons in during one fill up.
The fine folks who have come up with the X-Gauges and posted them on this site provided the Fuel Level (FLV) gauge and I have been watching it for about 10 tanks as I near the end of each tank. Twice I have driven until it is reporting .7 gallons remaining in the tank and with a full top off, I put in 11.785 & 11.88 gallons. Judgeless, I am assuming you did a complete top off if you put in 12.2 gallons and I'd say from the FLV information I have gleaned, you were very close to running out. Yes, I've heard the top off warnings and don't run out of fuel warnings.
I have also run the ScanGauge XGauge FLV down to 0.7 gallon twice. Without topping off, mine took only 9.9 and 10.0 gallons at that point. When topping off, how much extra do you put in after the first shutoff? The few times I tried, mine took only 0.25 to 0.3 gallon. The few times I've ever topped off any car were always situations where the extra fuel would be burned immediately, before thermal expansion can take place. I've watched too much gas flow out the caps of overfilled farm equipment warming in the sun. Don't know why dad never saw it.
I don't really watch to see how much I can get in after the first shutoff but I think it's between 1-2 gallons, and yes, I always fill up and do it like you, when I'm going to burn it off right away.
I read a some time ago when gas prices were out of sight that topping off is not efficient because some of the topped off gas is actually filling the hose to the car. So small amount measurements can be way off. They said at the time you are wasting money by topping off because you don't get the amount of gas you think you do. I have no way of knowing if this is right or not, but since then, I never top off my tank.
I have been debating on ordering one since I bought the car. I just placed the order. See what your post did.
It goes blinking crazy once it estimates that you have 20 miles left. I've only gone past the 20 mile estimate once. The the first click of the pump it took 9.65 gallons, which was about right for the Prius estimating 56.8. I haven't yet summoned up the courage to go into the reserve.
I usually put 10 to 10.5 gallons. I fill up until it stops, then add about .2-.4 more by filling slowly. I suspect some pumps are more sensitive than others and stop filling before it is really full. At one gas station I was able to put 1 more gallon after the pump stopped. This is usually not possible on the gas station I frequent most.
It's not courage when you live in the north. It's an unnecessary risk of safety... especially since when you stop to get gas, cleaning up the winter mess off the windows is beneficial anyway. In the summer, what's the benefit of that extra distance when you've already driven 450 miles? .
