I did the math..
 

Maybe I'll get blasted for this but I actually found this humorous. In fact it fortifies the reason I push myself to get better and better mpg tanks, always trying to beat my personal best. It is almost a hobby.

Ok, I added an air-dam and lower grill block using garden edging. I already had it lying around form the last car I added it to but lets say I spent $20 for the edging and zip ties. How long would it take to show a positive return on investment?
Lets go with 45 mpg without it and gain 1/2 mpg with the air-dam for 45.5mpg.
1000 miles driven / 45 mpg = 22.222 gallons used
1000 miles driven / 45.5mpg=21.978 gallons used
22.222 - 21.978 = 0.244 gallons saved
$3.85/gallon x .244 gallons = 94 CENTS saved per 1000 miles driven. Wow, awesome.
After 20,000 miles I have almost got back my initial investment.
Even if it brings a 2 mpg gain that would still only save less than one gallon per 1000 miles driven, or about $55 per year (@15,000 miles).

Was it worth it? You bet. Every new mileage increase adds up and is fun for me. As an added bonus, the goofy looking air-dam gets people talking and thinking about their own driving habits.

Wont get blasted or flamed for doing anything like that to a vibe around here.

Now if you put lawn edging on your CRX and went to a CRX forum you would get flamed because your lawn edging isn't a $400 uglyified fake carbon fiber aftermarket ground effects kit sold as "JDM" that required bondo to fill all the gaps in.

I'm wouldn't flame you, i do the math all of the time to see when a particular mod will pay itself back.

it's all part of being an ecomodder :)

That is too funny. The "left over" lawn edging I had lying around is from when I bought it and DID install it on my CRX (pictured in avatar).
I meant blasted for poo-pooing the actual miniscule dollar savings per mod.
Thanks guys. Just having fun and trying to put up good numbers on the fuel logs.

I am simultaneously blasting, flaming, and trolling you--in my head! :D

Just kidding. I would not have any idea what to say.

People ask me about this stuff, which is a very good question, but as has been mentioned before, is this really worse than spending much more money trying to make my car faster? The difference here is that we try to make sure that our modifications actually work and if they do not, we talk about it, and probably remove the modification.

right.
And, the largest gains in mpg are learned (driving habits, dfco, eoc, p&g, etc.) not bought. Free!
Another good gain is really really really cheap.. high psi in my tires. If you wanted, I suppose you could calculate the electricity I paid for to run my air compressor to fill the tires (tyres :) ).

See kids, math CAN be fun!

I often have the same conversation with others about when things will pay for themselves and I think that is why so many on this site are always looking for free materials and ways to do things cheaper. Prime example is pizza pans vs. moon discs :)

$55 could fill up your tank once a year though and for me one gallon every 1000 miles saved means that @ 15000 miles I've saved more than one tank of gas. So it's not something to sneeze at.

Wait, you mean these mods can pay for themselves? I need to get better at that.

I'm at less than a hundred bucks for all of my mods, including the sweet paint job, and 70 bucks went for adding the kammback alone.

Even though I'm pretty sure that kammback won't ever pay for itself in mpg savings during the life of the car, I did get a "wow, that looks better" from my wife (who carpools with me in that beast) after I took off the detached wing and added the kammback- - -so technically it's already paid for itself

I spent about 8 dollars on my antenna delete- if I only used the plasti-dip for that, and never used the extra washers (why can't they sell a one pack?!?!).

The improvement probably couldn't be calculated in a wind tunnel lol

But as you said it might be a hobby...it is one for me! I don't spend money on alcohol- so what some friends spend in a night can pay for a 4x10 aluminum sheet :D

I also look at it differently. Instead of looking at $ saved per mod...I look at it as $ saved over EPA.

I save about $50/month in gas vs EPA, so I see that as an extra $50/month allowance to ecomod.

As long as I don't spend more than $50/month on eco mods...I'm good!

Expanding on that thought; plenty of racers spend thousands of dollars grasping for that extra tenth, +1 bump in HP, or 1 more foot on the tractor pull. I've spent plenty on my other car so I'm willing to spends tens of dollars for another 0.5mpg for my other "performance" car :turtle:

And...driving smart saves gas money that can be used to drive smarter with by installing mods. Making it a self supporting hobby that can make/save you money at the same time.
Most of us need to drive so its a hobby within a requirement , multitasking at its finest.

Alternatively, you can think of it in comparison to options or aftermarket parts for your car. Often times mods to increase power end up costing 50-100 dollars per hp, sometimes more. Bling bling spoilers, wheels, skirts, bumpers, lips, etc. all run hundreds to thousands each.

If you can make some lawn edging look like it belongs there for 20 bucks, then aside from any possible benefits to your car it is already worth it :)

A bellypan that has secure mounting probably doesn't pay for itself either, but looking at the belly of your car and seeing no gaping holes and exposed frame/suspension/drivetrain is priceless. A nice exhaust would run an even higher bill, it's all in good fun and for the love of engineering and cars.

Also, to add to everything everyone has said, don't we do this because we ENJOY it? Personally, I enjoy eco-driving, I find it, especially with how much I drive, it gives me something to keep my mind busy at all times. I can't recall the last time I was 'bored' driving and mind you, I drive 5-700 miles a week.

Should do accounting LeMons style... anything you take off for economy's sake can be sold to redress the balance. :D

Selling stock big wheels and tires for 13's with skinny LRRs? Cha-ching!

Sell your passenger mirror! Pay for a kill switch!

I thought the general consensus here was that an airdam was good for 2-5%; even the modest 2% improvement would be good for about another mile per gallon. So while you're being conservative with your numbers, I daresay you're being TOO conservative.

Don't forget the savings snowball: if you don't need as much power to push your car down the road, then you're running the engine at a lighter load, less stress on moving parts, longer service life etc.

In terms of dollars per year, I think making the car go an extra few years is a savings that is both very real and very difficult to quantify.

Well elhigh, I hope I am too conservative and the next numbers come in good. I've only logged 3 tanks with my vibe and the first two were short ones to get a baseline on the board to compare to. Maybe I should have driven like the average dummy civilian and got their real world numbers so I could show much larger gains but I just can't. I have gone the right direction with every tank so far. With no electronics or aba testing I just have to watch my trend. I could show a slight loss with a poor tank even with a new mod that actually helped due to traffic or other circumstances.
Time will tell I guess

Just an FYI, the ~3 inch airdam I tried out on the 2014 Mirage didn't appear to be in that league. http://ecomodder.com/forum/showthrea...ini-29182.html

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davelobi, if you want your mods to pay for themselves faster, there's a simpler solution: modify a less efficient car. :)

At which point, it'd be more cost-effective to trade it in for a more efficeint car... :D

I'm actually glad I picked the Toyota Yaris sedan for my experiments after I saw your Mirage results... I wouldn't have gotten anything significant from what I did...

Didn't you have an Isuzu Crosswind?

I just did the math on the Kammback I added, and I'll have to drive the Black Widow another 26,000 miles to break even
It was an impulse buy, but I already forgave myself cause it looks way cool!

2.7 extra mpg over 58 avg (if the Kammback did that) = .046% increase in mpg
70 bucks cost of Kammback divided by 3.50 avg price per gallon = 20 gallons cost
20 gallons divided by .046 increase in mpg = 434 gallons to break even
434 gallons X 60.7 mpg = 26,344 miles to break even

Be careful what you spend on your mods, people . . . .some of them only sound like a good idea, but on paper, they don't really add up! That mod was only 70 bucks, and it will take over two years to recoup the cost, if my car lasts that long*

*sorry, forgot to add that my math does NOT factor in either coolness factor or bragging rights, which are very tangible though hard to put a dollar amount to . . .would I have bought that Kammback knowing the math ahead of time? Hell yes I would have!

I still do. But I had to tie the article in to a fairly new car to get readers interested. Nobody's going to read about my old hooptie... :p

I did the math
 

As sung to the music of "I fought the law,and the law won.":p

Lol:D