The Opel Admiral, subject of this post, was announced for 1937. According to its Wikipedia entry, only a few were built that year: the main production run was in 1938 and 1939.
Since development of the Admiral took place before Hershey's team arrived, it is difficult for me to associate its design to a stylist. However, it seems highly likely that Hans Mersheimer was involved.
The Admiral's styling interests me because of its odd collection of borrowings. The images below are mostly from the time the cars were in production, and their quality is mediocre.
The 1937-vintage Admiral's frontal design looks like it might have been inspired by this Volvo that must have been known to Opel body designers such as Mersheimer.
The initial facelift of the 1934 Chrysler Airflow featuring a more prominent grille. The Volvo PV36 was probably inspired by the '34 Airflow.
The headlight treatment (blending the lights into the hood) is similar to the Admiral's, and it is likely that its designers were aware of Hupp styling.