This is an annual show where there will be hundreds of German cars. I would estimate around 100 Porsches show up every year. This is the reschedule date. It was originally scheduled for May 1st but was moved for threat of rain. Many nice Porsches in the parking lot too. It's a concours but it's a wash and shine event as well. Not presumptuous at all. They usually have some kind of food trucks there so could be BBQ or something else.
Deutsche Marque Concours info link

Looking at last years results of the concours competition, they lumped all Porsches from 1965 to 1983 into the same class. 1st and 2nd place were 914s. See I told you it wasn't presumptuous...
Concours results - 914s placed 1st and 2nd for all Porsches 65-83