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2003protege 06-09-2008 02:35 PM

Juggling Cost of Mods with Payback Period
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Hey guys,

I made this spreadsheet up for myself and figured that I should let the community use it.

IIFFF there are no errors, and all the results I get seem reasonable, then this spreadsheet should be able to tell you how many weeks of commuting it would take to recoupe the costs of aerodynamic modifications based upon how much you spend, the increase in your MPG, your old MPG, and some other variables.

For example. If I did pizza pan aero-hubs for $10 and it gained 2mpg over my standard 38mpg, it would take 13 weeks for me to recoupe the cost.

Let me know what you think.

lunarhighway 06-09-2008 02:53 PM

nice! since i started thinking about mods that where NOT made out of garbage i've been calculating how long it would take to break even. problem is it's hard to say for certain how well a mod will work... there's al sort of persentages floating around on the web in relation to "some car" wich might be vastly different, also driveing speed and distance will have an effect...and without any FE monitoring tools it's hard to make out actual improvements form overall FE fluctuation. still every time fuel prices go up the more effective your mods get

2003protege 06-09-2008 03:08 PM

all correct. That's why I would suggest moddest assumptions when using this tool.

FYI. I ran numbers based upon what basjoos described in terms of his commute, and the cost of his modifications, and it looks like his mods pay for themselves at least twice a year. I would love for him to let us know the actual figure.

meemooer 06-10-2008 01:22 AM

Yeah but as the gas prices rise, that would mean the payback would gradually become sooner, right?

2003protege 06-10-2008 08:55 AM


edit - but the flip side is, if your payback period is split in half, it means you're paying twice as much for gas..

lunarhighway 06-10-2008 09:19 AM


edit - but the flip side is, if your payback period is split in half, it means you're paying twice as much for gas..
true but if you look at it in the most positive way;
it's nice to know a mod will pay for itself, but it's even nicer to know you're makeing money when that's happened, the higher fuel prices go the bigger the gain from even a slightly effective mod. And when you're buget's already stretched, sure one appreaciates those few solid dolars/euros you don't have to pay because of a little effort on your part.
spread over a year these saveings can ammount to much more than just some pocket change!

2003protege 06-10-2008 09:35 AM

So I'm interested to hear some actual numbers on proposed mods.

Personally, I'm planning on building a fiberglass kammback. It would cost no more than $60 and would hopefully give me at least 5 mpg. Just commuting it would take 30 weeks to pay off.

Anyone else?

aerohead 06-14-2008 03:15 PM

I like it a lot.Since I'm anal about mpg,during projects,I'm apt to let record-keeping fall by the wayside,and its very difficult to tell what I've actually invested in any particular project. And this is exactly what matters most to some people,when they ask me about my contraptions.Some kind of life-cycle-cost-analysis. If we can record and compile this kind of quanta,some potential modders should be able to build their projects completely on paper first,and know if the whole ordeal is going to be worth the expense in material and manpower before they ever leave for the store.Good one!

BluesDrive 06-14-2008 08:07 PM

I'm planning on building a lot of aerodynamic stuff on the car, eventually costing around $500 for me. Assuming I get even 5mpg out of it, that's already 65 miles, which is one way of a commute I do once a week. With rising gas prices, all those mods will be worth it within a good year or so. Gas around here went from 4.25 all the way to 4.59 within a week. Once gas reaches 5.00 I'm going to do my research and begin building the mods.

trikkonceptz 06-15-2008 12:00 PM

That's awesome ... I inputed all my expenses to date for the Vibe, including the Scangauge and with my killer commute, 110miles, I got a whoping 6 weeks until payoff, and oh well I have been doing this for 12 weeks, so I guess I'm in the money right now .. LOL

I must say I have a $200 investment in the car in order to get a 20mpg boost out of it, that's awesome, but alot is actually driving technique which is free no matter how you look at it.

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