In 1981 Tomy released the Flip Floppers series of action windup vehicles that did flips or spun around. The series included an antique car that breaks down, a buggy that flips over, a bus that spins and fluctuates its second level up and down, a helicopter that spins around, a propeller plane that flips over backwards, a car that flips over, a space shuttle that spins with an emerging astronaut, and a train that spins around. Pictures of these windups can be seen on this webpage.
With the popularity of Thomas the Tank Engine on Japanese television in the 1990s and Tomy selling other Thomas the Tank Engine toys,, Tomy also began retooling some of their other older toys under Thomas guises, including several of the Flip Floppers series.
This Double Decker Bus was released in red in the seemingly much more common U.K. and European releases, resembling a double-decker London bus, but this is the seemingly less common American version which is yellow - perhaps to emulate an American school bus?
This release was produced in Taiwan. This mechanism was later used for Bulgy the double-decker bus in the Mini Thomas series.
The windup mechanism has a lifting shoe that makes the bus spin around periodically. The upper level of the bus moves up and down as it runs.
The Mini Percy (ちっちゃいパーシー) released in Japan in 1997 and exported around the same time to Europe and the United States. Percy drives forward and then spins in place before picking a new direction to go in.
Percy's chassis has Thomas licensing information and is made in China. You can see where some portion of the tooling has been marked out... I'm not sure exactly what tooling this was adapted from.