I have pictures of my carbon build up at 30k that shows it does indeed work. I'll scan them and upload. I didn't do any "highway in 4th gear" though, I just went out and drove really hard for 20-30+ minutes at least once a month since I've had the car. I'm blessed with a place to do this though.. the highway option might be better for some. The few times I did a highway "burn", it was in 6th gear at 100+ for a long, long time. As a result of all this my car hardly showed any build up compared to what I've seen from others.
My service manager at Commonwealth VW tried to tell me if I only used Chevron and stopped occasionally using Mobil I wouldn't have any at all.. I thought about explaining direct injection to him, but instead I just