Comment by maffyoo

Comment by maffyoo 15 hours ago

31 replies

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When see things like this, I always think of the Chinese proverb

"An inch of time is worth an inch of gold, but it is hard to buy one inch of time with one inch of gold"

Which always says to me that its not worth it just use the quickest option

Take the example drcongo posted:

"Yesterday I had to drive to a nearby town, just 20 minutes away, and noticed that every single petrol station there was a good 5p per litre cheaper than my town. I might plug this into a map."

Assume he uses 30 litres a week (high end of average UK usage) that's £1.50 per week saving but assume the extra miles use half a litre, that takes about 65 p off the saving (ill not go into wear and tear) over 30 years of work 50 weeks a year this means a saving of £1,275 over 30 years ... sounds a lot but

20 mins away - this assumes 40 minutes per week over 50 weeks is 2000 minutes, and over 30 years 60000 minutes. Now assume you are awake for 16 hours a day this equates to 62.5 days of free time - more than two months of awake time

so as the saying goes... which would you prefer £1,275 saving or 62.5 days of time

entuno 15 hours ago

I almost never go out of my way for fuel, because as you say, it's rarely worth it once you factor in your time (never mind the fuel spent).

But it's still useful to know about price variation so that you can plan ahead. I regularly drive past several different petrol stations, and if I know that one of them is usually cheaper or usually more expensive then I choose to use or avoid it, or to decide that I'll fill up tomorrow when I'm going that way rather than today at a more expensive one.

And that'd be more useful built into satnav, so that if I know I have to fill up somewhere along my route then I can pick the cheapest place, since there's no real time cost to any of the options compared to each other.

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  • maffyoo 14 hours ago

    totally agree, technology could make this much more cost effective (or time effective). what's the best use of my time versus the cheaper option..

    It's interesting running the numbers though. e.g. if it only take 10 minutes to get cheaper fuel, how much cheaper does it need to be for your time to be worth more than the UK minimum wage (£12.21 for adults over 21)

    based on my maths (from above calculations) it needs to be about 7p per litre cheaper to justify the extra 10 minutes and for your time to be worth more, per hour, than the minimum wage.

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    • ElevenLathe 6 hours ago

      I once had the idea to do something like this, though the intention was to pitch it to gas station operators as a way to keep their prices competitive (i.e. alert them when the station down the street drops their prices so that they can too and not lose business to casual price shoppers or, alternatively, when the station down the street raises their prices, so that you can too and not lose revenue needlessly) and learned that there are a couple entities, at least in the US, that have national data here. I couldn't even figure out how to contact one, and when I called the other I was essentially laughed off the phone by someone with a VERY New York accent -- it seems from context that their data is VERY expensive and used by Wall St. types, so the idea of some nobody from flyover country essentially reselling it to mom & pop gas station operators was funny, and out of the question.

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    • entuno 14 hours ago

      Also depends on the size of your fuel tank and how full it already is. The time taken to refuel is (almost) the same regardless, but if you've got a 40l fuel tank vs a 70l one or you're only half-empty then it's going to be less worthwhile.

      7p cheaper for 10 minutes works out at about minimum wage if you're buying 30 litres, but with a bigger car you could easily be buying twice that, which works out much better.

      Although of course you also need to factor in how much fuel you burn driving to the cheaper place, and the extra wear and depreciation on the car. If you take the HMRC standard rate of 45p/mile (which was meant to cover all of that kind of thing, but hasn't been updated for years) then even going a few miles out of your way quickly ends up costing more than it's likely to save.

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    • notahacker 9 hours ago

      mostly such tools are useful when you go very close to a few petrol stations on your regular routes anyway. I can pretty much time topups for when the cheapest station locally is en-route to my destination

      A 7p per litre difference does sound like the difference between local station and motorway prices though, and they probably will have factored in that opportunity cost of time...

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      • alexfoo 7 hours ago

        > A 7p per litre difference does sound like the difference between local station and motorway prices though, and they probably will have factored in that opportunity cost of time...

        Only 7p?

        Motorway services have shocking price markups, way more than 7p. Most people don't realise this or are just too lazy to find something that isn't quite as convenient.

        According to the live feed at https://www.rac.co.uk/drive/advice/fuel-watch/ I see:

            Unleaded is 131.80p (UK wide) and 156.80p (Motorway Service Area).
        That's nearly a 20% markup.

        Last time I drove into a motorway services and saw prices ~20p/litre higher I just drove through the petrol station and found a local garage to fill up at.

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maccard 11 hours ago

Sure. Now imagine your car’s GPS knows you have 60 miles in the tank, and your journey is 300 miles. It can query the APO and figure out what the best petrol station to refuel on your journey is.

More information is always good.

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balderdash 4 hours ago

It would be really nice if say apple maps on my phone when connected to airplay could get the Fuel level in my car and distance to empty, and then when you plug in a route, and press add a gas station to my route, it picks the best one based on time out of the way, how much fuel you have left, and best relative price. ideally you could set your preferences in the app (e.g. never more than 5min out of the way, below median price if less than 1/8 tank, lowest quintile price if >1/8 tank etc.

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citrin_ru 14 hours ago

Driving somewhere to fill the tank 5p/l cheaper probably waste of time but unless all your trips are very short you usually can find a petrol station along a commute roue or along the route of a long leisure trip which is cheaper than one closest to your home. When you see prices in your navigator it's much easier to do.

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  • mnw21cam 6 hours ago

    Agreed. Most of the time the cost of driving out of your way exceeds the saving you would make. However, there's a fuel station near me that is 19.8% cheaper than one only 1.6 miles away from it, and that's a thing that is worth knowing.

    https://xkcd.com/951/

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alias_neo 14 hours ago

As someone who waits until my tank is almost empty, to visit Costco one per month for a fill-up, despite it being 5 miles away, I understand your point.

However, I think (and hope) the point of this service is that by being public, it'll drive prices down for drivers.

I drive 10 miles round-trip once per month to save what I guesstimate is £5 on a tank of fuel, then spend £100-300 in the Costco store while I'm there. I'm not the target audience, but I hope that for those who drive regularly, or for a living, this can help route them to where they can get the best prices as they're passing by.

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MilaM 14 hours ago

Driving 40 minutes to save 5p might not be worth it. What does make more sense (at least where I live) is to go to the petrol station in the late afternoon or evening instead of the morning hours. The intraday price span on most regular fuels is usually 10 Euro cents per liter. Weekends also tend to be cheaper.

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123pie123 8 hours ago

It can be more complex than that, sure for one person your comment makes sense

but if enough people use their time to go to the cheaper station further away, then they may force the closer garage to to reduce their price

either that or the close garage goes out of business and the one further away puts up the price because they can.

but still, it can be more complex

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  • Kinrany 8 hours ago

    This is like saying that selling enough volume might make up for losing money on every unit. It's only complex until you do the math

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ksec 12 hours ago

>so as the saying goes... which would you prefer £1,275 saving or 62.5 days of time

Just want to say, nothing wrong with doing that. Everyone has different priorities. I just hope most wont have to do it.

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oniony 15 hours ago

I've also wondered about whether to fully fill my tank or drive on a small amount so that I'm not using fuel to carry fuel. Do you know of any metrics on that?

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  • embedding-shape 15 hours ago

    I haven't made any calculations, and it's more a hunch, but considering you usually need to remove hundreds of KG in order to make an impact on how much fuel is being spent, 40-50L of gas (~40KG difference between full and empty maybe?) would have an marginal effect on how much fuel is spent to carry a full tank vs 10% filled tank.

    Besides, with a smaller tank, you'll make more trips to tank it, and also have less choice to go to gas stations that are further away but have cheaper price. Then again it becomes a question of "Do I want more time or more money?", back to square one :)

    Edit: Also, someone correct me if I'm wrong, but doesn't the fuel pump use fuel itself as a coolant or something? Never investigated myself, but some car-knower once told me that running the tank on low always isn't good for the fuel pump, or something like that. If that's true, running with 10% of the fuel would mean more maintenance too, potentially removing any savings in the first place.

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    • jansper39 7 hours ago

      > Never investigated myself, but some car-knower once told me that running the tank on low always isn't good for the fuel pump, or something like that.

      The main issue is that it risks pulling detritus from the very bottom of the fuel tank, usually a bigger issue in diesels and I suspect less of a problem these days.

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      • embedding-shape 6 hours ago

        Aah, I have a diesel car, maybe that was what he was alluding to! Car is from 2017 so not that old. Thanks :)

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    • alias_neo 14 hours ago

      > doesn't the fuel pump use fuel itself as a coolant or something

      I know very little about these things, but my understanding was always that any form of liquid pump uses the liquid itself as coolant to some extent.

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      • embedding-shape 14 hours ago

        Yeah, fair enough, I think what he mentioned though, wasn't just about fuel going through the pump being used as coolant, but some extra process that only happens when you're not running below say 10% or whatever, an extra cooling process that only runs when you're not low on fuel. Maybe I misunderstood him though and it's just about the liquid passing through.

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        • alias_neo 14 hours ago

          I think the fuel passing through is the only method that could be used to cool, the volume of fuel required is presumably constant, regardless of how much fuel you have left, so the amount passing through the pump should be the same until you run out.

          On a related note, my car has a fuel heater, to pre-heat the Diesel before it hits the engine, I assume this is typical in modern cars, but using the fuel as a coolant would presumably contribute positively to this desire for warmer fuel entering the cylinders.

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  • maffyoo 15 hours ago

    you can probably work it out but you have to make a lot of assumptions :)

    Ultimately how much is your time worth? in the example given drcongo's time is worth £1.28 an hour.

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  • fragmede 14 hours ago

    Unless you're driving a lorry with a 120L tank, it's negligible. We're talking like, 100 mL per 100km.

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tialaramex 14 hours ago

If your priority is the journey to fill a car with fuel and time spent doing so, surely just buy a Battery Electric Vehicle and then this problem evaporates because it just plugs in like every other appliance you own rather than needing a trip to a fuel station.

Shopping around for the fuel of an EV you can do from a web browser, oh hey, Octopus have a good deal for night charging, click click done.

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teamonkey 8 hours ago

The typical use case is probably much more like deciding which station within half a mile of home is cheapest, and that could easily be a variance of 5p or more.

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drcongo 13 hours ago

Well that saved me from trying to work it out, thanks!

edit: My annual milage is actually very low, so it definitely wouldn't be worth it, but I appreciated the maths either way.

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delaminator 14 hours ago

You didn't factor in the amount of taxpayer money spent on creating the website and the ongoing costs of running it.

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