I heard that there once was or once was proposed an engine supplier loyalty reward that increased the effectiveness of an engine that a manager had been loyal to.
Thanks Ian. :) It's true that we no longer apply this 'familiarity' value as we called it.
It may be reintroduced in future updates but if it is it will be clearly labelled. It was a hidden factor before, and we removed it because it was too confusing for managers to determine what effect it was having on performance.
It is my understanding that we long ago removed any significant vague or hidden factors from the simulation to make the results more manageable for the players. Mind you, driver error is still hidden, as in we don't provide the exact amount of driver error for each lap. That value will be included in a future update.
It's the largest part of what people call the "qualottery" (Driver error). It can account for several tenths per lap of inconsistency in some cases, and can be quite a factor in qualifying results. There are ways to reduce it, but it's always present, just as in real life.