i still havent seen any mpg gains from my exhaust u put on over a year ago, theres just too many underpasses around here

 

It is only a 1-2 MPG increase driving the same route I do everyday and remaining on the same power level that I use on my CTS. Like said above, it is from better lubricacity of the injectors and fuel system. Now, I think if I use the AMSOIL diesel concentrate with cetane boost, I will see even more of a increase. May try it on my next case purchase.

 

Did you add the price of the Diesel concentrate to the price of the Diesel fuel tank fill? Do you still have a mileage gain?
They sell a Diesel fuel in Germany called ultimate Diesel. It is 10 Cent more expensive than normal Diesel. It has a 5 point higher cetane number. So the Diesel shall run smoother. It really does run quieter.
They also claim a mileage gain. It doesnt work. Because it has the same BTU as regular Diesel.
Friction of the fuel pump and injectors is neglectible compared with friction of the crank and the piston rings.