Suggestion: refined advanced vehicle fuel

Let oil + sweat refine to a vehicle fuel that adds say 20%(?) speed, well or engine power, I'm not sure about how the physics work exactly.
that advanced fuel together with sweat again could refine to an even better fuel with +10% additional speed.

not sure about the magnitudes, at some point physics may look strange but sometimes that's the case already on the other hand, I had sweat in mind because of the time=money (free to play) concept.

Interesting idea, but I think 20% speed increase is WAY to much

ok, too much.

maybe +8%/+4%, and +2% when a third time for the PvP guys