The garage is seen twice in the film. The first time is when Himmler tells Fegelein that he's secretely negotiating with the Allies. The second time is when Günsche phones Kempka to ask for 200 liters of gasoline, necessary for Hitler and Eva's bodies cremation.
In Downfall Parodies
The garage is where the Speermobile arrives to bring Speer as well as to send Himmler away. This is the place where Himmler and Fegelein have meetings with the antic dealer Albert Speer to buy Antics from him and discuss several ways of getting the nerves of Hitler.