Regulation of concentration/fraction of substances in an exhaust stream

A method for regulation of a concentration/fraction of one or several substances in an exhaust stream in a motor vehicle through control of a driveline of the vehicle, wherein the motor vehicle comprises:

• a driveline comprising a combustion engine, driving wheels, mechanically connectable and disconnectable from the combustion engine, and an exhaust system configured for removal of an exhaust stream from the combustion engine;
• the method comprises the step:
• controlling the driveline to activate coasting of the vehicle or to deactivate coasting of the vehicle, based on one or several first parameters P1 for regulation of a concentration/fraction CEx/XEx of one or several substances TEx included in the exhaust stream, at least one of the one or several first parameters P1 are a first concentration/fraction difference between the first concentration/fraction C1/X1 in the exhaust stream and a reference concentration/fraction CRef/XRef,
• wherein coasting is activated by mechanically disconnecting the combustion engine from the driving wheels, and
• wherein coasting is activated while the vehicle is moving.