Minivan Kardboard Kammback boosts MPG +3.7% (6.6%, counting roof rack delete)

[dichotomous]

Originally Posted by MetroMPG

At $3 gas, 6750 highway miles/year*, 23 mpg = $58 savings. Less as gas drops, more as it increases obviously.

Another note: the speed of testing was just 89 km/h / 55 mph. Actual savings of course increase with speed.

(* that's 45% of EPA's average annual distance of 15k miles total city+hwy)

right but to build it out of anything even semi permanent is going to cost more than that...

though, 6% is a good number, and nickle and diming works both ways so it could help to lead up to an impressive deal. but wouldnt a small roofline extension and short side extensions give almost all the same benefit? (I felt I should actually add something productive instead of whining about a giant kamma) cause thats something that would more likely be put on more vans an such, a few short little extensions could look cool even

[trebuchet03]

Originally Posted by dichotomous

right but to build it out of anything even semi permanent is going to cost more than that...

though, 6% is a good number, and nickle and diming works both ways so it could help to lead up to an impressive deal. but wouldnt a small roofline extension and short side extensions give almost all the same benefit? (I felt I should actually add something productive instead of whining about a giant kamma) cause thats something that would more likely be put on more vans an such, a few short little extensions could look cool even

Since $50 is nothing, please paypal $50 to my eMail address (trebuchet03 at gmail dot. com)

That said, a few short extensions likely will have nowhere near the same magnitude of effect. Over a 10 year lifespan, $50/year is $500.... And if you get another minvan, odds are that if you built it in the first place, you can adapt it to the new one

Kidding aside

Car Talk

Going from 100 to 200mpg isn't as effective as going from 10 to 11mpg This is why I think we should be using gallons per 100 mile rather than mpg. It's much easier to see the difficulty in sipping less fuel when the asymptote is 0 and not some unknown mpg number

21.5mpg = 4.65 g/100mi
23mpg = 4.34 g/100mi

100mpg = 1.00g/100mi

[red91sit]

Originally Posted by trebuchet03

Since $50 is nothing, please paypal $50 to my eMail address (trebuchet03 at gmail dot. com)

That said, a few short extensions likely will have nowhere near the same magnitude of effect. Over a 10 year lifespan, $50/year is $500.... And if you get another minvan, odds are that if you built it in the first place, you can adapt it to the new one

Kidding aside

Car Talk

Going from 100 to 200mpg isn't as effective as going from 10 to 11mpg This is why I think we should be using gallons per 100 mile rather than mpg. It's much easier to see the difficulty in sipping less fuel when the asymptote is 0 and not some unknown mpg number

21.5mpg = 4.65 g/100mi
23mpg = 4.34 g/100mi

100mpg = 1.00g/100mi

BOO!!! as much as I enjoy memorizing random integers (3, 5280, 12, etc...) I would still prefer seeing us switch to L/100 Km. I've heard some other countries have already converted to the metric system! haha.

[trebuchet03]

Originally Posted by red91sit

BOO!!! as much as I enjoy memorizing random integers (3, 5280, 12, etc...) I would still prefer seeing us switch to L/100 Km. I've heard some other countries have already converted to the metric system! haha.

I figure it would be better received using an apparently more patriotic British system... oh the irony

[aerohead]

Darin,do you think Canada would mind if Washington D.C. used you for the next 4-8 years ? There's a guy headed there,come January 20,'09 that could use you in his cabinet! With 200-million vehicles on the road,all these little 6.6% would mean an awful lot.--------------- Nice goin'! P.S. Does CAD/CAM involve masking tape?

[MetroMPG]

Ha! Phil, I'll only do it if you and several other members will let me put your phone numbers on speed dial! I figure I'd be pressing that button a lot, since there are sharper knives in the EcoModder drawer on this subject matter.

Masking tape would work, but I prefer duct tape for some reason. Maybe I should switch. The duct tape leaves an awful mess behind.

---

FYI, I've updated the first post with the details of the test for anyone who cares.

Checking my calcs, I also discovered a small error that caused me to understate the effectiveness of the mod by a very small amount (3.7% actual vs. 3.6% stated originally).

[Christ]

Hm... 0.1% difference in actual vs. stated.. to the positive. Shoot him!

We all make mistakes, man. on the work though. What would be great is if we could all make something like this for relatives and non-immediate family/friends that looked aesthetically presentable, didn't change the vehicle's drivability, and still had a decent impact on mileage... kinda like changing your friend's light bulbs to LED or Fluoro bulbs when they don't know it.

Is it wrong to mess with your friends by changing the hidden bulbs in their house? I say no. It helps them, it helps the environment.. anyone that could get mad about that needs to get a hobby. Like helping to save the environment! LOL.

Anyway, back to the original idea: IF we could all get something that would aesthetically fit the vehicles of our loved ones, and give it to them for Christmas, it would be like giving the world a Christmas gift - Slightly cleaner air for all! And they'd never know it, they'd just think it was a cool thing for their car to add on.

[MetroMPG]

On that topic (what's aesthetically acceptable), today I was shovelling my car out of a snowbank and a gentleman getting into his car nearby said: "hey, that's quite a 'bonnet' on the back of your car". Referring to the Kammback, of course.

So I chuckled and asked, " you want one for yours?"

He immediately answered "NO!", then smiled and drove away.

I wonder what it would take for the average person to see this as a "cool thing".

[duaneb9729]

Hey Metro,

if your giving away kambacks, i would like one for my isuzu npr box truck! would love to see how i could get the mpg up!

i am joking of course, as to the free part anyway its very interesting to me, and i am in awe of the folks that go out of their way to do the mods then take the time to share them! ty !!

[MetroMPG]

No problem - it's very interesting to me too, and fun on top of all that.

A couple more photos, FYI:







I think it's important to repeat that this was a super quick 'n' dirty "fabrication" using the a pretty conservative 10 degree top & sides angle. It could no doubt be optimized for even better results.

But not by me! I've got my own car to work on...