Fuel maximizer ?

Anybody have any experiance with these so called fuel maximizers found on e bay? I just purchased a 07 big horn with a hemi and these tings claim 4 mpg and 35 hp increase sounds to good to be true but if it only gains 2 mpg for 20 bucks it would be worth it.No matter what its going to look good pulling my 65 coronet to the strip colers nearly match.

The std for fraud is "if it sounds too good to be good it probably is (too good to be true)

If it does not prominently advertise that
it has been proven in a
SAE/TMC Type fuel economy test
.. Then there is a 90% chance that
It is a fraud.

The big 18 wheel trucking companies
and the Society of Automotive Engineers
help develop these highly accurate and repeatable ways to find out what works and what is "snake oil"

For example

http://www.ooida.com/Benefits&Services/Discounts/Dipetane/SAE-J1321-Dipetane-Test-Overview.pdf

http://www.pavetrack.com/PAVE/Type%20IV%20Fuel%20Economy%20Report%20for%20Omega-Tec.pdf

http://www.airtab.com/aeroflow.html

http://cleanairfleet.com/uploads/SAE-ClaudeTravis.pdf