The one matte grey car I saw at a dealership had the kit in the back. It was opened but unused. The salesman said it was a fingerprint magnet in the showroom and they clean it almost daily - it was getting a lot of attention and people sitting in it every time I was there. Your dealer probably used the OEM kit for that.
I took my blue VT to a hand wash place that often has a lot of flashy rap star and professional athlete looking cars being detailed. Initially the guys were unfamiliar with the VT but when I picked it up the manager asked if this was the car that comes with a matte finish option. He went on to say that they wash several matte finish cars and had the special equipment and cleaners to handle the job properly. So you might want to look in to some of the hand wash places in your area. It may not be practical to use them all the time but you could see how people that wash matte Lamborghini's do it and what stuff they use.
I took my blue VT to a hand wash place that often has a lot of flashy rap star and professional athlete looking cars being detailed. Initially the guys were unfamiliar with the VT but when I picked it up the manager asked if this was the car that comes with a matte finish option. He went on to say that they wash several matte finish cars and had the special equipment and cleaners to handle the job properly. So you might want to look in to some of the hand wash places in your area. It may not be practical to use them all the time but you could see how people that wash matte Lamborghini's do it and what stuff they use.