Not sure if it's general behaviour or just the difficulty I'm on (85). But the AI cannot overtake another AI car that is slow in the corners. But it also can't get past on the straights because the slow car is going full speed. Last race for Catalunya with Renault and Alpha Tauri P1/P2 becuase the Mercs/Red Bulls/Ferraris wouldn't overtake. The faster strategy was to 2 stop, which all the top 10 did. But what this did was after their first stop the "leaders" got stuck behind the long stinters. On the map it looked like there was a safety car. After the 1 stoppers pitted it mixed it up a little, but then the leaders pitted again and the same thing happened. I can get past if I get my elbows out which seems to open it up for the faster cars. I don't mind it mixing it up a little, but it was like watching a couple of safety cars going around the track and is putting my rivals in high points positions.