"NissTech" <haywood_jablowme@[EMAIL PROTECTED]
> wrote in message
news:481535f2$0$7066$4c368faf@[EMAIL PROTECTED]
> Urban Legend
>
> This theory was disproved on Mythbusters an while back
Which theory? I love Mythbusters, but sometimes they don't think
through their "proof." I think they did a good job with the tailgate
up / tailgate down myth, but not so sure on the tonneau cover. As I
recall, they showed no improvement for the tonneau for their
particular vehicle and a maximum speed of 55 mph. I am not sure you
can say this is generally true for all pick-ups and higher speeds.
55 mph is really not fast enough to make definitive statements about
issues related to aerodynamic drag and fuel economy. It is in the
range of the speed where aerodynamics becomes the primary influence on
fuel economy (the actual transition point varies by vehicle). It is
close enough to the transition point that other factors may still be
primary, and mask the effects of aerodynamic improvements.
I don't think comparing the mileage for one or two tankfuls of gas is
going to prove anything in this case. The change in mileage is going
to be small (probably on the order of a few percent at the most).
Unless you have a lab set-up, you need to compare many miles of
highway driving with and without the tonneau to come to a valid
conclusion. A gas mileage log book would be essential to drawing a
decent conclusion.
Ed
> I'm glad your getting better mileage but I don't thing the cover is
> causing it
>
> "willshak" <willshak@[EMAIL PROTECTED]
> wrote in message
> news:1sGdnYPcBrOlx4_VnZ2dnUVZ_s-pnZ2d@[EMAIL PROTECTED]
>> The beginning of this month I bought a soft tonneau cover for my 97
>> Nissan PU, 2.4 l, 4 cyl FI, 62,500 miles. He's a good old boy and
>> looks almost as good as when he was new. I buy him a present every
>> once in a while. Last time it was a cat-back dual exhaust, and the
>> time before that, a keyless entry system.
>> When I installed the cover, I had about 3/4ths of a tank of gas
>> left. Since driving it with the cover on, it seemed that my trip
>> odometer was getting a higher reading compared to my gas gauge than
>> before. I usually traveled 50 miles between the 1/4 markings on the
>> gas gauge, winding up with about 190 miles with about an 1/8th tank
>> of gas left when I refill it. I got to 212 miles with about an
>> 1/8th tank left. When I filled the tank yesterday and made the MPG
>> calculations from my last fill up, it seems that I was getting
>> 18.34 MPG. I rarely put more than 11-12 gallons in the 15-7/8
>> gallon tank. This time, it was 11.595 gallons.
>> Before the cover was installed, I was averaging around 16.5 MPG.
>> The last time I filled up before the cover, I got 16.62 MPG. I
>> haven't changed my driving habits despite the rising gas prices, or
>> made any long trips, so it may be aerodynamics.
>> The next time I fill up, the MPG will be calculated with having the
>> cover on for the entire period between fill ups, so we'll see what
>> develops.
>> Watch the mpg drop and burst my balloon! :-)
>>
>> --
>>
>> Bill
>> In Hamptonburgh, NY
>> To email, remove the double zeroes after @[EMAIL PROTECTED]
>
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