I have been seeing these gizmos on Facebook that you plug into your car/truck's OBD/Diagnostic port that will increase fuel mileage, boost preformance, etc. I have a 2014 GMC Sierra 1500 4wd 5.3L that I would like to get better fuel mileage. Now I get 17-19 mpg. Does these things work? If so, which one should a guy get?
Jason
Jason