  This paper investigates the performance and fuel-saving effect of a velocity
control algorithm on modern 50 cc scooters (Euro 5). The European Parliament
has adopted major CO$_2$ emission reductions by 2030. But modern combustion-
powered scooters are inefficiently restricted and emit unnecessary amounts of
CO$_2$. Replacing the original restriction method with the system presented in
this paper, the engine's operating point is being improved significantly.
Therefore, a Throttle-by-Wire-System senses the rider's throttle command and
manipulates the throttle valve. A redundant wheel speed sensor measures the
precise vehicle velocity using the magneto-resistive principle. The entire
system is managed by a central ECU, executing the actual velocity control,
fail-safe functions, power supply and handling inputs/outputs. For velocity
control, an adaptive PI-controller has been simulated, virtually tuned and
implemented, limiting the max. velocity regulated by legal constraints (45
km/h). In this way, the environmentally harmful restrictors used today can be
bypassed. By implementing a human-machine interface, including a virtual
dashboard, the system is capable of interfacing with the rider. For evaluation
purposes a measurement box has been developed, logging vehicle orientation,
system/control variables and engine parameters. A Peugeot Kisbee 50 4T (Euro 5)
is serving as test vehicle. Finally, the system has been evaluated regarding
performance and fuel efficiency both through simulation and road testing. Fuel
savings of 13.6 % in real-world test scenarios were achieved while maintaining
vehicle performance.
