At least Honda's personnel adored Senna precisely because of his fussiness, which they interpreted as care/dedication and which on their judgement exceeded Prost’s (hardly known for not caring about his cars).
There’s an outstanding Brazilian biography written about Senna (that unfortunately was never translated to English, probably because it lacks sensationalistic appeal) by the journalist Ernesto Rodrigues. He took the time to interview the Honda personnel (Nobuhiko Kawamoto, Yoshitoshi Sakurai, Takeo Kiuchi, Osamu Goto, and a few mechanics too) and while they make it clear that the engines were all similar, from their statements it becomes clear that in their heart of hearts Senna gradually became the favourite.
This went back to the Lotus days, and one of the episodes they mention is that once in testing Senna parked the car on the grounds that the engine was about to blow up. As there was not a sign of smoke they did not take him seriously but once they opened the engine they realized he was right. By the time he went to Mclaren, the Japanese admit that they were happier in their demeanor to work with Senna because on Sakurai’s take, not only they perceived Senna as faster but his feedback was judged to be much more detailed than Prost too. And because of that, they naturally started structuring engine development around Senna’s preferences. The specific example Sakurai gives is that Prost preferred a smoother, rounder powerband, while Senna preferred a peakier, more abrupt one.
So while one can imagine why in that context Prost started feeling pushed aside, until proof in the contrary, his claims of having inferior equipment were/are mistaken.
Edited by guiporsche, 26 November 2018 - 23:29.