The design of a 6-pole inner-rotor permanent magnet synchronous machine with buried V-shaped NdFeB-magnets for a power of 24 kW (contin.), 48 kW (short-term overload) at , with a maximum speed , is described for the use in a medium-sized hybrid-electric car with double-E-drive and range extender. Based on the specifications of this vehicle with a two-stage transmission and two identical electrical machines, one of these synchronous machines is designed electromagnetically, mechanically and thermally for a high power-to-weight ratio via an intensified liquid jacket cooling. This led to the construction of a prototype machine, which was thoroughly tested. The test results at no-load and load conditions are discussed. The effectiveness of the chosen cooling system is verified by temperature measurements; the tests show that the prototype machine has a certain reserve, so that the final machine design can be done cheaper and more compact.