The sailing function makes the most of situations in which the car also has sufficient momentum to freewheel forward. Such situations include country roads with a slight downward gradient or longer stretches of straight road approaching city limit signs. Intelligent clutch actuation systems from ZF then temporarily disengage the combustion engine so that it doesn’t suppress this kinetic energy. These can be electronically controlled and activated by wire, providing the basic prerequisite for the sailing function.
The disengaged engine can then idle while consuming a minimal amount of fuel. Ideally, however, it stops completely for a short period of time, because this is the only way in which zero emissions can really be achieved. “It is ultimately the vehicle manufacturers who decide how this concept is integrated into a car,” says Buhl. “Meanwhile, we have further developed the sailing function, turning it into a sailing manager that can react even better to each driving situation.” Modular software elements make it possible, for example, to connect the feature to a navigation system or ZF’s adaptive cruise control (
) and also enhance it by adding a traffic flow or rolling resistance detection system.