Well, I ran my old foam touring car on the new carpet over the weekend, and it was a lot of fun. I was only about 1/2 second slower than my 1/12 car, even with it low on power. The tires lasted multiple runs without even fully losing their as-cut texture, and I had to re-learn some stuff about foam touring like how they often run best with tight diffs full of thick grease. Losi Smart Diff grease was the ticket.
I also realized that when it comes to lapped traffic, nothing has ever quite bumped a slowpoke out of the way like a foam touring car. They are hard to upset.