How are you calculating Fuel usage?

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Gil

Gil

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old-guy64
This is a little different than the "What are you paying for fuel?" thread.
The universal answer to that question is TOO DAMN MUCH!!!
anyway:
I found myself reading an article on MSN or one of the other websites related to fuel economy.

The article stated that it was more "realistic" to throw the MPG (miles per gallon) calculation out in favor of MPD (miles per dollar).

I've been using this lately and my 28-31 MPG Camry got a whopping 7.5 MPD when I filled up today.

When applied to a 40 MPG car you improve to 10.4 MPD (at $3.87/gal)

So, anybody else calculating this way?
 
8 1/3 MPD in my Escort.

That's 35 mpgs at 4.20 per gallon.
 
I’m not sure I understand why that’s considered more “realistic” – the only thing MPD does is introduce the cost variable (MPD = MPG/Price-per-gal), and the only thing you can do to change that is go to the cheapest gas station, which you should be doing already anyway, in which case you can treat it as a constant. If anything, calculating MPD will make it more difficult to determine how your driving style (or the state of your car) is affecting your mileage.
 
But that’s the thing – that’s an independent variable that you have no control over (except, as I mentioned, going to the cheapest station). Maybe I’m wrong, but I assume that most people who keep track of MPG (other than for expenditure reports) do so because that gives you information on whether or not you’re driving with a lead foot. MPD introduces a variable that has nothing to do with that, and therefore skews your data in a way that’s not helpful.
 
But the equation is a great way to figure out what you're paying for fuel at the time. It factors in fuel efficiency to figure out how much it costs to keep your vehicle running.
 
yeah, but what if fuel goes up. am i getting less per dollar if i paid a lower price? even if i stull have half a tank, does my miles per dollar get calculated on the price i paid for gas, or the current price of gas. and what if im out of town for a conference or something. do i have to factor that rental car milage in?

that doesnt make any sense.
 
You're all being Sage-y. I think the point Gil is trying to make is simply that with this calculation you can see how far a dollar gets you... and the answer is 'not very freaking far.' It was surprising to me to read his figures. I had never thought of it like that. Mine are probably lower.
 
M5Power
You're all being Sage-y. I think the point Gil is trying to make is simply that with this calculation you can see how far a dollar gets you... and the answer is 'not very freaking far.' It was surprising to me to read his figures. I had never thought of it like that. Mine are probably lower.
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But there's not much point in knowing how far you go on a dollar. Even if you drive very economically your MPD can be high by going to an expensive gas station because you're lazy. It doesn't give you any incite as to how you're driving, or what to do to improve that.

Joey D
I still just use the miles driven in a tank/gallons put in. I think I'm averaging about 36mpg in the city and I can easily get 40mpg+ on the highway.
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This is what I've always done. Cruising between 75 and 80 I recorded slightly above 30 mpg in the Del Sol. I'm not sure about the Si, because it's more aerodynamic but it's heavier. Plus, I haven't had any highway trips long enough to make an accurate measurement.

How do you go about doing the in-city measurement? Isn't your city driving interupted by highways during a particular tank of fuel?
 
About 90% of my driving is city so I just figure that the 10% on the highway doesn't really affect the overall mpg.
 
neanderthal
yeah, but what if fuel goes up. am i getting less per dollar if i paid a lower price? even if i stull have half a tank, does my miles per dollar get calculated on the price i paid for gas, or the current price of gas. and what if im out of town for a conference or something. do i have to factor that rental car milage in?

that doesnt make any sense.
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You will be getting less miles per dollar than if you paid more for fuel because that dollar bought less fuel than if gas was cheaper and less fuel is going to get you less far. I'm not sure what Gil was talking about in terms of half a tank, but I'm guessing that asking how far you would get if you put a dollar of gas in teh tank now is a better way to measure what you are paying for fuel at the time. And I don't see how a rental car would play into this at all. That car would get a totally different figure getting pretty different gas mileage at different prices.

Maybe it just makes sense to me.
 
Keef
But there's not much point in knowing how far you go on a dollar. Even if you drive very economically your MPD can be high by going to an expensive gas station because you're lazy. It doesn't give you any incite as to how you're driving, or what to do to improve that
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oh2005dui.jpg
 
Philly
You will be getting less miles per dollar than if you paid more for fuel because that dollar bought less fuel than if gas was cheaper and less fuel is going to get you less far. I'm not sure what Gil was talking about in terms of half a tank, but I'm guessing that asking how far you would get if you put a dollar of gas in teh tank now is a better way to measure what you are paying for fuel at the time. And I don't see how a rental car would play into this at all. That car would get a totally different figure getting pretty different gas mileage at different prices.

Maybe it just makes sense to me.
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the dollar paid the same amount for the fuel. if you drive differently that changes the equation in terms of consumption, not in terms of price paid. the price paid is in the past, it has happened and you cant change that.

the rental car comes into play because
a i have to pay for it. does that factor in. my car is already paid for.
b i have to fill it up. do i have to avg that with my cars fuel economy. im travelling. thats measured in miles isnt it. so dont i have to factor that in.
 
M5Power
oh2005dui.jpg
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Yes, their driving could have used some work. But we're talking about gas, not how to get three DUIs.
 
neanderthal
the dollar paid the same amount for the fuel. if you drive differently that changes the equation in terms of consumption, not in terms of price paid. the price paid is in the past, it has happened and you cant change that.
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If you pay more you get less mpd since you paid more for the same amount of fuel.

neanderthal
the rental car comes into play because
a i have to pay for it. does that factor in. my car is already paid for.
b i have to fill it up. do i have to avg that with my cars fuel economy. im travelling. thats measured in miles isnt it. so dont i have to factor that in.
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Why would you bring the cost of rent into a "fuel consumption" equation? And why would you average fuel economy over such a long term? Wouldn't it be better just to do it between fill-ups or something similar?
 
neanderthal
the dollar paid the same amount for the fuel. if you drive differently that changes the equation in terms of consumption, not in terms of price paid. the price paid is in the past, it has happened and you cant change that.
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You paid the same for less fuel. And if you drive differently, yes that will change a consumption equation, similar to how it will change the mpg equation. And the miles per dollar equation is not a price paid equation. The only way to calculate price paid is to go and fill up your tank, which is independent of miles. I will pay the same to fill my tank if I drove 400 miles on the highway or if I was jsut racing through the city. again, miles per dollar is what you are paying to keep your car running. It takes into account both fuel prices and fuel mileage, which pump price and miles per gallon cannot do alone.

the rental car comes into play because
a i have to pay for it. does that factor in. my car is already paid for.
b i have to fill it up. do i have to avg that with my cars fuel economy. im travelling. thats measured in miles isnt it. so dont i have to factor that in.
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A) The car itself is not fuel. Rental fees come into play when you bring the cost of ownership into account. A leased car would be very similar to a rental car. All of a sudden, Joey D's MINI would not get nearly as far per dollar when you take his lease payments into account. And both lease payments and I believe rental fees are independent of mileage driven. That's just one more variable (constant?) that would have to be distributed over the entire function which doesn't even pertain to it in the first place.

B) A rental car is a completely separate trip. Totally different factors mean it would be a totally different situation. You wouldn't factor what your rental cars got mpg-wise into the mileage your regular car gets.
 
Actually, I guess the real question here, is with calculating fuel usage in this way do you find that your travel is being curtailed? or, is easier to cut back due to knowing just how miles every dollar is taking you?

I know that my "side trips" and fun runs have gone by the wayside.
 
I'm having a hard time seeing how this is valid, that or it seems confusing. :dunce:
 
V1P3R
I'm having a hard time seeing how this is valid, that or it seems confusing. :dunce:
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Who gives a flying flip about validity?:sly:

I was really just trying to stimulate some conversation and deeper thought.
I am also tired of worrying that I might just have to either win the lottery, or get a job closer to home, so I can afford to go to work.

I thought I just might spread the worry a bit and see how this fuel crisis is getting to everyone else.
 
I'm sorry to say dOOd that I feel like I'm in a FAR better situation than you even if I drove really bad and my MPG went down. I mean, I thought $53 for 12 gal. of gas was bad, but you... Man. It's gotta hurt pretty bad any way you calculate it. :lol:
 
V1P3R
I'm sorry to say dOOd that I feel like I'm in a FAR better situation than you even if I drove really bad and my MPG went down. I mean, I thought $53 for 12 gal. of gas was bad, but you... Man. It's gotta hurt pretty bad any way you calculate it. :lol:
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Actually, my daily driver is a 30 MPG Toyota Camry. (Still 7-8 Miles per Dollar)
I have access to a 38 MPG Civic, but I'd have to let my son drive my Toyota, and the 6-8 MPG ain't nowhere near worth the comfort difference I'd have to endure in the Civic.:lol:
 
Oh... damn it. stupid 20 yr old car. :grumpy:
 
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