This was created by Bob Parsons and he claimed significant MPG
increase using this device. He actually kept a very detailed record of
his gasoline consumption, throughout his travels, but sadly, he passed
away last year.............
If the link does not work, it's in the photo section, album #58.

http://autos.ph.groups.yahoo.com/group/subaruvanagon/photos/browse/912a

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Gracias,
 Miguel