I start looking for gas stations at 3 pips, and fill up while I still have 2 left. I see no reason to intentionally get lower than that.
I fill at two pips, generally. Once upon a time I drove a diesel car, and you NEVER let those suckers run out!! Having to get your injectors primed is a pain in the arse! (not to mention, costs $$) I got in the habit of just keeping my vehicles fueled up.
I start thinking about filling at half tank, and will usually do so when the first opportunity presents itself.
I voted when the last pip starts flashing but I'll clarify that. I typically go up to 20 miles after it starts flashing. If it starts flashing on the way to work I'll fill up on the way home. If it starts flashing on the way home I'll fill up the next morning on my way in. I live 20 miles from work hence the approximately 20 miles.
I try to fillup at Costco on Saturday or Sunday if it's less than 2 pips. If it runs down to 1 pip on a workday, I'll swing by Costco because my kids drink a gallon of milk a day and milk is cheapest there too! Hard to believe milk is cheaper than gas now. Kids run on milk, why won't a Prius?
I voted 2, but usually fill at 2 or 3 depending on circumstances. I have seen 1 pip once, never let it go to flashing. Typically when I refill I get 7.5 to 8 gal in the tank. I have only gone over 10 gal twice, both times gas came shooting out when the pump failed to shut off (BGTS - barfing gas tank syndrome).
I read a few years ago that it's bad to run really low on gas because it makes it more likely for sediment in the fuel tank to make it to the fuel filter, thus prematurely clogging the filter. I have no feeling for the veracity of this warning, but it can't hurt to heed it.
I read a few years ago that it's bad to run really low on gas because it makes it more likely for sediment in the fuel tank to make it to the fuel filter, thus prematurely clogging the filter. I have no feeling for the veracity of this warning, but it can't hurt to heed it.
I'd not heard that rationale, but have always thought that keeping the tank full or close to full during the winter was a good thing, helped prevent condensation from forming in the tank and freezing the fuel-lines. I suspect that the bladder of the Prius might eliminate that problem, which may even be a form or urban myth, but I still follow the 'full tank' principle during the winter, especially when it is very cold (teens F or colder). I voted 'three pips' and that is a probably good summer average for me. Running out of gas sucks.
That was a real potential problem years ago with steel fuel tanks but I wouldn't worry about it much anymore. I suppose however there could be some left over plastic shavings from modern plastic tanks floating around somewhere.... Regardless I don't think there's much potential for sediment in a Prius' bladder. This is however my opinion. Mike
Like Mike mentioned, years ago it wasn't a good idea to let the tank run dry before you filled it. Rust was a bigger problem back then, and has basically been solved by plastic type tanks or better protection of the inside of the tank. With the fuel pumps inside most gas tanks today and having replaced a number of them, I haven't seen to much junk or plastic shavings in them. Big, Big Problem: Are the foil seal(er)s from things line gas line anti-freeze, fuel injector cleaners, well almost anything you'd add to your gas tank. These little foil seals fall off the bottles and then wind up in your tank. Get low enough on gas and the pick up tube will start to suck them up. Problem goes away when you fill up the tank. I've dealt with a few of these! Keep the krap out of your tank!
Answer: it depends. In my normal around-town driving I wait until the last pip starts flashing. I'm rarely more than a couple of miles from gas. If I'm in unfamiliar territory I'll start looking for a place at one non-flashing pip. "Unfamiliar" for me still generally means in or near civilization. If I was on a long stretch of isolated highway more common out west than in these parts, I wouldn't go that far.
In the Winter I fill up when I'm close to 400 miles (I commute 49 miles 1-way). In the Summer I can push it to close to 500 miles. I usually end up on 2 pips, but sometimes it 1. And occasionally I get the flashing pip close to home.