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This paper reports on the development and testing of a compact and mobile CVS system for the measurement of particulate matter emissions of diesel passenger cars. It consists of the same components as a conventional CVS system but needs much less space. Reducing the size of the CVS system was achieved by the optimization of the turbulent flow in the dilution tunnel by the use of an optimized mixing chamber, in which the engine exhaust gas is diluted with filtered ambient air. The measures taken to improve the turbulence in the dilution tunnel lead to the same effect as a tunnel with dimensions according to the legislative regulations. All the components of the mobile CVS system are arranged in a very compact design, so that the new system has a size of only about (1.70 x 0.80 x 2.10) m. Due to the mobility which is possible with such a design, the new system can be quickly adapted to different engine and vehicle test cells for passenger cars.

In the near future, technical demands for powerful electric motors integrated into the drive train can be fulfilled. These motors combine the functionality of starter and alternator offering a higher electric power than conventional alternators. At low engine speed, they can work as a motor and introduce an additional driving torque in the drive train (booster). The required introduction of suitable electrical storage devices enables regenerative braking to reduce fuel consumption significantly. In this paper, for homologation tests and customer use, the potential savings of regenerative braking are shown for a variety of engines, vehicles and test cycles.