Oh ok, thank you for seconding what Starscream's affirmation.
It would have made sense to have the talk with an austrian accent, as I think the choice for the german language comes from the fact that back when the book Dracula was written, Transylvania was part of the austro-hungarian empire, technically in the hungarian part of it, but I think german was the only "official" language of the empire, hungarian, romanian and various slavic languages were only spoken by farmers.
Since Dracula was a "noble" his native language was probably german, although this is not specified in the book (or did I miss it ?). All that is specified in the book is that he learned english perfectly in both written and oral forms, and only using books (before they could include audio tapes or CDs in language methods
) which sounds totally impossible, even for an undead creature. This made me smile.