I think it might function like one of the old Brio trains, where it would look for a chip inside a special piece of track and say speed up or blow the horn.
Also - Shinka Gear!
EDIT: Just looked, and that's just it. Red Track makes it go fast, green makes it go slow.
Also - Shinka Gear!

EDIT: Just looked, and that's just it. Red Track makes it go fast, green makes it go slow.