The objective of the Hy-Nets project is to develop a novel approach for improving the resource and energy efficiency of connected hybrid cars: hybrid propulsions on a test bench will be coupled with an environmental simulation of the vehicles as well as of the communication between the connected cars. This way, new insights can be derived of their influence in realistic city environments. We plan using the city of Paderborn as an example of a typical European city to assess the potentials of hybrid propulsion in combination with networked cars.