How can one distinguish a “fake” fuel saver from a “true and efficacy” one? 

Truth regarding fuel savers may be found in:  

1. The references that each single fuel saver has obtained through time.
2. uthority of those whom have referenced.
3. Scientific value of test done.

1. Clearness: The references must clearly indicate the entity that has tested and undersigned the reference, specifying name and title of those in charge of testing indicating all data of the same such as name contact numbers, email address, with details regarding the Protocol/procedure of testing.
   
   
2. Authority: The reference should be obtained through qualified and competent entities such as INTERNATIONAL RECOGNISED LABBORATORIES, WELL ORGANISED FLEETS ETC.
   
   
3. SCIENTIFIC VALUE OF TESTS:  Test must be done following internationally recognised Protocols (SAE – EPA); both on road and in Laboratory. Measuring fuel consumption on hydrocarbon vehicles is certainly neither simple nor easy.
   

There are serious and scientific protocols to follow when testing both on road and/or in laboratory:                                                            
Gas emission test and fuel consumption test.
The price of a fuel saver must be compared to and among those products that have demonstrated their efficacy. While, those products that have not given demonstration of their efficacy through the points above, must be left out/excluded.

Therefore, all those references which do not have the obove mentioned characteristics must be excluded, for example, those references issued and undersigned by unknown people stating they have registered a fuel consumption reduction of x %, without specifying how and  what procedure was followed to determinate that result or simply stating that his vehicle used to have an average monthly consumption of “y” which has now been reduced to x %.  It is necessary to underline that most of the clients do not reflect over the following: every time we run 100km (for example) we will register a different consumption which is influenced by load transported, path, wind, climate, traffic, estate of use etc; therefore each month the average consumption will be different with fluctuations which could go over 20%.   As result the data obtained do not have any scientific value, as the same “epa”has confirmed.