At our club, we use two types of cleaning car:
1- Dry "Magnet cleaning car": This is a home-made cleaning car that is made with magnets simply put under any car. It is amazing how much fine metal particles this "Magnet cleaning car" collects every time it is used. The magnets showed below can be found at hardware stores. They have a perfect size for the O-Gauge (1-7/8" wide). It works especially well on Atlas tracks because magnets do not stick to Atlas tracks.
2- Wet CMX-O-HR – Clean Machine™ O Scale “3 Rail” (High Rail)»: We use it with Isopropyl Alcohol, 99%.
The combination of these two cleaning methods (Dry + Wet) have been used successfully for over year at our club.
Daniel