 I have heard that in the past also, and I think what happens is if you're driving it hard, the turbo gets hot, and you risk overheating it and doing damage if you shut it off too soon. So I'm not sure if it applies to your specific car. The training that I had was on earlier diesel pickups around the late 90s, early 2000s. And to your point, when you're done with a hot drive cycle, let it idle and let the cool oil cycle through for a few minutes. You're not going to hurt anything by doing that for sure.