AeroRanger (brother to AeroJeep) boat-tail

[cons]

Matt's VW got a 12% increase in mpg with the rear wheel skirts, pizza pans, and grill block. His boattail/kammback is stalled because he didn't like the aluminum flashing (it's loud and doesn't bend well). So he is waiting on plastic or foam to finish it.

[cons]

Just did an 82 mile hwy loop , 60 degrees out, a bit windy, had to stop 5 times, sometimes for a few minutes. When I filled up, I waited a couple minutes so no gas in the tank was sloshing. Then filled it. Let it settle another minute, then topped it off a click, trying to be as precise as possible for a short fill. Got 60 mpg.
Now, as Frank Lee will point out, it was a small fill, so it's something to take with a grain of salt. But, beforehand, after getting some pure city driving out of the way, I filled it up, got in 1/4 of a gallon, with 16 mpg. So I think there is some truth to this. Further testing is needed to verify the 60 mpg, but it's a great start. And with the 5 stops (all coming to a stop from 60 mph, and not a long coast down), I feel more strongly that there is some truth to it. We'll see.
Lastly, I have a feeling being at 6,200 feet elevation might play a role in the generally excellent mpg this summer, over my spring mpg in Seattle.

[cons]

I'll do another test run Monday. I might drive 100 miles to see if that improves accuracy. But I don't want to drive all day to get a big fill-up. Anybody have an opinion on how many miles it takes to get a solid reading?
Also, the truck is 1,500 miles overdue for an oil change. So I'm hoping that could boost it a wee bit too.
At the gas station again, so many people were inquiring. I might print out a bunch of business card type sheets with this website and some basic drag stuff to hand out. A magazine might be interested in doing an article on ecomodding. I'll try to steer them to Darin and Phil for more accurate statements.

[Zerohour]

Very nice! Alot of duct tape holding it together, but if it works, it works! That would be amazing if you could pull 60mpg with a pickup!

I'm curious, did you leave a way to access the bed?

Also, the way your wheel covers mount up are a really good idea!

[cons]

Thanks Zerohour. Yeah I can still access the bed because the boattail is on a hinge.
I'm still not officially saying 60 because it's a small fill, one-time event. I got 50 mpg though on the test run without the boattail, so I am optimistic.

[Zerohour]

But you need to consider the boat based on original highway. If you get 5mpg, thats 20% of the original highway rating. If you're even touching 60 on occasion its just awesome!

Kudos to you, can't wait to see the data results!

[cons]

Yeah I was wondering if I should expect increases off original EPA ratings or after the mods. Still not sure on that. Is it the law of diminishing returns or the sum is greater than all the parts? I think it's the latter.
Also, after further thought, something tells me this is all just way too high. Maybe these short fills, which are consistently 60ish, just aren't accurate as Frank Lee always says. I don't know. I don't know how they couldn't be (even when I'll max the tank out on the return), but I don't know how it'd gain so much. So I'm just going to drive half the tank out, which will take a couple weeks. After that, I've got a long road trip and will get a really good idea. But I don't want to be disappointed to be getting only 40 mpg then.
A big problem has been people at work putting gas in and out of my tank, reducing me to these short runs when I fill up before and after. I just bought a locking gas cap today though so that'll stop. And I got an oil change and it feels much smoother.
So, I think I am hitting 60 in ideal flat, non-windy conditions, but I'm not too confident on it. If the aerocivic can hit 120 though, I think 60 could possibly be what I 'm getting. I'm just remaining skeptical for the moment.

[KamperBob]

Originally Posted by cons

I don't want to be disappointed to be getting only 40 mpg

40 mpg with any pickup is nothing to be disappointed about. You're greedy. But I like it.

Cheers
KB

[cons]

YEAH BABYYYYYYYY!
Just did another test run, same stretch, 60.56 mpg!
I really feel like there's something to it since the previous run, same stretch was 59.77 mpg. Here's the differences:
1st run: had to stop 5 times from full speed, some slower driving involved.
2nd run: little windier, ran the fan a little bit, noticed the pass. side mirror was opened (closed it half-way through run w/o stopping!), had an oil change couple days ago, drove 45-60 the whole way, no slow downs, no braking.
Did the same fill-up style for precision: pull up, wash the windshield so the gas has time to settle, fill-up, start filling out mileage details on my chart (kills another minute), then top off one click. Same gas station.
Before this, here's the following fill-ups:
0.25 gallons, 16 mpg (purely slow driving and lots of stop signs)
1.372 gallons, 59.77 mpg (pure hwy)
1.530 gallons, 23.53 mpg (mostly town)
2.114 gallons, 36.899 mpg (mostly hwy, but a bit of town)
1.321 gallons, 60.56 mpg, pure hwy, pretty ideal conditions except for some cross-winds

NOW, I'm ready to calm down and do a bigger tank for my commute. But I really feel strongly about this. Lastly, I DO believe being at 6,500 feet elevation helps. Think about how baseballs and golfballs fly way further up here. The air is less dense so it gets pushed around the car easier. Maybe the oxygen/fuel ratio is the same, but that's only part of the equation.

Thoughts?

[KamperBob]

Originally Posted by cons

I DO believe being at 6,500 feet elevation helps. Think about how baseballs and golfballs fly way further up here. The air is less dense so it gets pushed around the car easier. Maybe the oxygen/fuel ratio is the same, but that's only part of the equation.

Thoughts?

Usually thinner air at elevation leads to richer mixture and less efficient. The rule I recall is a normally aspirated engine loses 2% max power per 1000' elevation. So 6500' should pay a 13% handicap compared to sea level by all rights. Then again, maybe you know something others don't...

Cheers
KB