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Old 08-05-2008, 11:34 PM   #14 (permalink)
Modified Driver
Twerp's Avatar
Join Date: Apr 2008
Location: South Western middle of nowhereish New Hampshire
Posts: 104

Frozen Tundra - '03 Toyota Tundra 4WD SR5 Access Cab
90 day: 26.51 mpg (US)

Red Skateboard - '91 Honda Civic DX
90 day: 45.49 mpg (US)
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I think mine will be pretty practical once I cut out a section of that center bulkhead. Then there will be a nice amount of usable space under the thing. I should be able to accommodate most types of cargo that I carry with the exception of my four wheeler. Plus, now my bed should be water resistant!

I've actually attached it to my truck and I got to drive with it on my way to work tonight. I got to make some seat-of-my-pants observations and initially, they look promising. I'll do all the nice sciency stuff when I have it 100% completed. For now, I've seen roughly about a 1mpg increase. There are a few caveats which make that more interesting though. First, it's not completed. There is a decent sized gap between the cap and the cab which is prolly destroying some of my air flow. On my way to work, I was, well, a little excited and as a result maybe a little heavier on the throttle than usual. I was also trying to maintain higher speeds to take more advantage of the aero improvements. If I had to guess at what my mileage would have been with the heavier throttle and no cap, the cap may have caused closer to a 2-3mpg increase.

It seemed like it coasted a little better at the 40-55 mph range, which is the fastest that my commute gets. During one of the EOC downhills, it approached speeds 2-3 miles faster than usual. Nothing is very precise about these observations and there is a ton of variables that could make them invalid, so I won't know anything for sure until I can do some hard, precise, number-based testing. For now though, it looks promising. And my personal educated guess is that once the gap is filled, I could see a 2-4 mpg increase on my commuting mileage. For any other trips which involve a lot of highway travel, my mpg increase might be more significant. That's what I'm hoping, anyway...
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