I hear this all the time but it can’t possibly make a difference. If the pump sucks gas from the bottom of the tank it would pick up settled sediment regardless of whether it’s full or not.
I sit corrected. It was the user manual in a rental we recently drove. Hertz messed up our reservation so we got a free complementary upgrade to a 2017 Land Rover Discovery Sport.
What a crap vehicle.
Anyway, the user manual says:
I mentioned earlier that I routinely ran my old car down to <5 miles to go without issue. The owner’s manual on my new (used) car says to avoid running it below 30 miles to go, warning that “vague nebulous mumble damage may result.” We shall see.
Now that we’re in hurricane season I keep all vehicles at >1/4 tank and top off when the 5-day future weather forecast gets even a little bit interesting. Most of my fellow Floridiots ignore any and all hurricane prep until the wind speed at their house tops 40mph. That’s about 8 days after NWS sounds the first advanced alert.
I feel I should add that while I’ll cheerfully drive until my car drops below 30 miles remaining (alleged) and stops displaying it, I also live nowhere near a disaster area and pretty much never leave town - I’m always literally within two miles of a pump. And that’s if I’m picky about where I fill.
When I leave town, no way is it getting much below a quarter.
Same thing here for my commuter car. I pass through 3 distinct pricing areas going to work so I can usually save a nickel per gallon by choosing which side of town I gas up in. Usually I gas up during the trip that starts below 1/4 tank. Or if a weekend is coming. Or a winter storm.
I used to be dumber than I am now and once I found myself out of gas while driving through the wilderness.
I was driving up a long hill which pooled the fuel to my disadvantage and when the engine was starved the vehicle jerked fairly hard and, presumably, what little was left in the gas tank splashed around and landed in the fuel pickup.
This gave me another 10 or 20 seconds, or so, until it happened again. Repeat a couple dozen times. Very hard on the vehicle. I know, I’m an idiot.
When I crested the hill and returned to flat travel there was no more splashing of fuel and my seconds were numbered. I came to a stop in the middle of nowhere, on some native reserve, directly in front of a little house that was perhaps 50 feet from the road, with an amused looking man watching my plight from his balcony as he nursed a beer.
“Hey there. Say, you wouldn’t happen to have any fuel, would you?”
“Sure, come.”
So, out behind his house we flipped over his lawnmower and filled a 1 litre coke bottle. 2-stroke or 4-stroke? I can’t say I cared.
“Thanks! What do I owe you?”
“Oh, whatever.”
So, I gave him $10 and I was on my way. I did make it to a gas station.
My wife freaks out when it gets to the 1/2 point and is a constant nag on trips to fill up once it reaches there. Myself I let my car down to 1/8 before I look to fill up.
I usually get twitchy when I get down to a half tank, so that’s when I fill. I can’t remember the last time I’ve been as low as a quarter tank.
Maybe I’m the only one like this?
mmm
I think it’s worthwhile spending some time deciding how to decide when to fill. That is, any one fillup is not a big deal, but whatever thinking leads one to adopt a policy of filling at 1/2, or filling at 1/4, or filling with a range of 70 or 10 – that thinking is actually pretty high value thinking. Especially if you keep a car for a decade, like I do.
The goal ought to be to minimizing both gas station visits and running dry events, perhaps minimizing the running dry events to zero with fairly high confidence. The two big signals I look for from my car is guidance about how fast I’m going (I’m one of those people who tries to always go the speed limit and no higher), and whether I should be buying gas.
My car’s range indicator only shows increments of 10 miles. I wish it showed integer miles, not because I want to run it down to 3 miles, but because the accuracy of the system helps dictate how I use it, and they’ve introduced significant noise just by the choice of digit display. I’d like the European ideal of an accurate indicator described above, and want to think about the cushion myself, not have it hidden.
The fuel pump and contamination discussions are interesting.
Diagrams online show that my own fuel pump is inside the fuel tank. Does it need fuel around it to keep it cool? Or does it merely need fuel flowing through it to keep it cool? I think this changes the range by perhaps 30%. The manual urges buying fuel when the light comes on, not at the 1/4 or 1/3 tank level. I think fuel flowing is the issue, not being submerged, but it’d be nice to confirm that.
But I really don’t see how nearly emptying the tank is going to put a bunch of contaminants through the system. It’s already sucking from the bottom of the tank. Solids, at least the ones that sink (which most would), and water, are all going to get drawn up preferentially. Clean gas should be the last thing sucked up before air.
On long road trips I usually plan run it down to the 50 mile warning in picking out a place to refuel, which I usually do in advance. But more often than not I’m too conservative and reach that station before the warning. If I haven’t scoped out where to refuel and in area/time of day without a lot of open stations I do it as soon as possible after reaching 1/4 (which is >100 miles highway). I never run it down right down to end to see what happens, owners manual says that can damage the car and I’m not interested in finding out if they are being too conservative about that. The car’s trip computer is slightly optimistic on gas mileage compared to actual results, but I assume it’s slightly pessimistic on where ‘empty’ really is, like most cars.
Around home we refill a little below 1/2. Back during Sandy our supposed ‘free market’ governor (Christie) arbitrarily put in gas rationing by plate number (I thought we got past that nonsense back in the 70’s: ration by price, everyone is better off in the end) and I had to drive somebody to DC on the ‘off’ day. Glad I had the gas to get to DE.
That’s why the true cost of buying and reading a book on my Kindle is actually $874.32.
And I lost over $8,000 last year showering and using the toilet.
You ignored my response and just repeated your assertion in the OP that it’s “worthwhile”, but I think we agreed on the quantification: the potential saving from this type of decision process is of the order of 7c per gallon of gas (valuing your time at around $50 per hour). How long you keep one car for seems irrelevant to me.
That quantification at a potential saving of 7c a gallon gives us a sense of whether it’s really worthwhile to optimize fuel strategy in the way that you envision. And bear in mind that the 7c saving does not factor in the greater risk (and cost) of running out of fuel occasionally. Plus, of course, valuing your time at $50 an hour is dubious, and really only applies if you’re driving for work on a strict hourly rate, and you have no other reason to use the facilities at a gas station anyway.
It seems to me that 7c a gallon (around 3%) is probably dwarfed by considerations of fuel economy in the car that you choose to buy and by driving at fuel-efficient speeds.
I agree on ‘time worth $50/hr’ any such analysis, based on work time income, would only apply in exceptional cases. The trade off is much more likely to be one non-remunerated activity v another. Stop for gas a few less times a year therefore watch a few minutes more junky TV, or spend a few more minutes quality time with loved ones, deliberately chosen examples to show how hard it would be to nail down a relevant cost of leisure time. And we don’t drive to work, so getting gas at a little <1/2 tank when we’re around home comes out to every ~20 days, usually together, and forced full service in NJ, so we sit and chat. I’m not sure there’s any opportunity cost to at all to doing it every 20 rather than every 30 days.
On road trips it’s more plausible to say, even though still not directly related to income, that more hours on the road is fewer at the destination, nor are you having fun driving the car during fill ups (if you like to drive), and with self serve you’re standing there not sitting comfortably in the car*. But with our car’s ~500 mile range to the 50 mile warning, we stop for bathroom and meals more frequently than for gas. It’s hard to come up with any kind of valid $ savings by running down to <1/8, but I generally do, on long trips to known places with gas stations open at the arrival hour.
*not to defend NJ’s policy which is silly IMO, standing there a few minutes, not a big deal either way.
Your response was correct in saying the potential saving from this type of decision is of the order of 7 centers per gallon. Sorry, I actually misread your response the first time, thinking you were saying the entire labor cost of filling was 7 cents, not the savings associated with optimizing the fueling strategy. But on re-reading I understood, and, yes, I agree.
How long I keep the car is relevant because I want to spend the time now to choose a strategy that I can use for ten years. If I bought a new car every year, I’d have to settle on a strategy ten times as often, and a more careful strategy becomes more expensive as part of the whole picture.
I agree the kind of savings we’re talking about is probably dwarfed by fuel economy and driving speeds. But, I choose my cars by studying Consumer Reports and looking for total cost of ownership including fuel economy. I wound up with a highly reliable and fuel efficient station wagon with 4 wheel drive, the station wagon form and the 4 wheel drive being my other priorities. So having a little fun figuring out a fueling strategy is consistent with the way I did those things too. And I always drive the speed limit, so the driving speed issue is covered too.
Yeah, this is not that obvious a thing, I think. There’s the base pay rate as a general figure for comparing my time to money. I don’t know a much better one. I could argue that I work five days and then get two days off, so my time off is 2.5 times harder to come by than my work time, and then the $50 becomes $125. When I see the weeks flowing rapidly by, and think of how few days I actually get to do what I feel like doing, this sounds appealing. I could also argue that saving a few minutes on errands like buying gas has never improved my income that I know of, and the cost is zero.
Not that many activities translate so neatly to money. For example it’s weird to contemplate the cost of sleep. But the effort of buying gasoline does translate to money in a pretty straightforward way.
I will say that it was very pleasant getting a new, reliable car, and one of the pleasant surprises was that it went much further between refuelings. That got me wondering how refueling figures into the whole package of owning a car, and hence the thread. I can imagine some day choosing between two otherwise similar cars, one of which had a couple hundred miles more range than the other, and asking if that was really worth several hundred dollars more, and there being a real answer.
My car just has the light that comes on when there’s a couple of gallons left. But it sure seems like it doesn’t come on sometimes until the gas is not insignificantly lower than the alleged threshold, so I don’t like to do a lot of driving after I notice it’s on. That’s not a game I’m eager to play.
My car is 14 years old, and I saw it’s “gas needed” icon for the first time today.
I did something like this, in 1966. In a 1965 VW bug, with a (nominal) 10.6 gal tank, I deliberately ran it dry, since I had a full 1 gal can with me. The gauge was mechanical, not electric, and proved to be very accurate.
From then on, I was confident enough to drive from St. Louis to an oasis on the Chicago Tollway, 330 miles, and still have some gas left. Worked every time.
Almost every Canadian I know will agree with this. (The rest are fools or live in Vancouver.) There was at least one occasion back when I was a teen where I would have frozen to death in the ditch if I was unable to keep the vehicle running while I waited for my tow truck. I strongly recommend that if you live in a place that has dangerously cold weather that you do the same.
In the two months that pass for summer around here, I run it until the low fuel light comes on. I can get about 30 km out of it from the point.
I think the smart way to look at it is in terms of relative value of time, not tank condition. I try to fill up my tank every Sunday, no matter how full or empty. Sunday afternoon time is cheap and plentiful, and it means I never have to worry about filling up my tank with precious weekday time, either when I’m running late to work or are eager to get home. It also makes mt life predictable and orderly.
I don’t always follow this regime, but when I do, I’m happier.