Here is a larger version of the factory shot Art posted, so you can see a hair more detail. One thing you'll see a bit better is the wheel weight holders in the rims, which add a nice detail to models of these cars.
http://www.autowp.ru/pictures/mercedes-benz/500k/autowp.ru_mercedes-benz_500k_sports_sedan_2.jpg
Here's the other side:
http://www.autowp.ru/pictures/mercedes-benz/500k/autowp.ru_mercedes-benz_500k_sports_sedan_1.jpg
Here's a later 1939 540K coupe which, to my mind, is less graceful than the 500K version (PS: This is a great site for all kinds of car reference, though it's a bit short on interior and engine detail):
http://www.schlegelmilch.com/archive/index.php?PHPSESSID=fcde54ba4fcc1a909355e755810eb3af&page=search&offset=0&mainid=80161&select_auto_manufacturer=5&select_auto_model=327&st=0