The article describes a design of a microcomputer system which is realized in the educational scale model control for physical principles demonstration. That particular design project was a part of the educational facility complex project called Experimentarium aiming at basic school and high school students. The article introduces two racing car models controlled by a microcomputer. The first model set demonstrates the speed and acceleration calculation based on a real time measurement. That calculation result can be compared with results obtained during a running man experiment. The second car model set demonstrates a downforce keeping the car riding the ceiling with wheels upside down. The microcomputer control system is based on microprocessors by Atmel, and the system is described in details including illustrative pictures, schematics and graphs.