Took me about four or five tries today with my 911 GT3 RS, and it's not even equipped with all of the best parts yet (not trying to brag here, by the way). It's tuned to be quite drifty, which helped me get around the slight turns efficiently on the highway without losing much speed. But it seems I was still somewhat lucky here, as I think someone crashed out behind me as they were exiting the highway through the final loops. Plus, I kinda had to hope that the AI wouldn't slam me at all.
Based on what I've seen through my attempts, I agree that this is a difficulty spike that should probably be addressed.