Nymphenburg Park is in the west part of Munich around 15 minutes from the city centre and is easy to reach by public transport:
All S-Bahn lines except no. 7 to "Laim", then bus no. 51 to the "Schloss Nymphenburg" stop or
Underground line U1 to "Rotkreuzplatz", then tram no. 12 or 17 to the "Schloss Nymphenburg" stop

From motorway A 8 (Stuttgart - Munich):
From the end of the motorway, continue straight on along Verdistraße as far as Nördliche Auffahrtsallee, and then turn right, following the signs to "Schloss Nymphenburg".
From the A 96 (Lindau - Munich), exit "Laim":
At the traffic lights turn left into Fürstenrieder Straße, keep straight on, go through the Laim underpass (here Fürstenrieder Straße becomes Wotanstraße) and continue to Romanplatz; turn left at Romanplatz (in the direction of the Stuttgart motorway) into Notburgastraße, and then turn left at the bridge, following the signs to "Schloss Nymphenburg".
From the A 95 (Garmisch - Munich), exit "München-Kreuzhof":
Keep left at the München Kreuzhof exit, which will take you into Fürstenrieder Straße. Keep straight on, go through the Laim underpass (here Fürstenrieder Straße becomes Wotanstraße) and continue to Romanplatz; turn left at Romanplatz (in the direction of the Stuttgart motorway) into Notburgastraße, and then turn left at the bridge, following the signs to "Schloss Nymphenburg".
At the palace there are around 450 free parking places for cars and 25 parking places for coaches.
Route planners you can find at
http://auto.abacho.de/routenplaner/.