There is no rubber banding per say, but I remember Rushy saying AI adapts to your speed (in a realistic manner).
"Realistic" in the sense that if you're driving slowly, the field of AI will slow down to let you catch up, and if you're performing especially well, it makes the field suddenly able to outperform you, and potentially during the same race. It's super easy to abuse as long as you're paying attention to how much of the race is left, and the first couple times you get all the time stars without getting the podium star in a tour event (and then see the opposite when you go back to earn it), you'll see how goofball it is.