Sauerbraten with a 1.1 pound beef rump roast
Sauerbraten is meant to be cooked low and slow (schmoren), not like an American roast which has to be removed from the oven as soon as it reaches a target internal temperature. Keep both the oven temperature and the 4 hour time, do not remove it after it reaches the target temperature. 

For some background, read SAJ14SAJ's answer to How can you tell when a roast is done?. It is the section on low and slow roasting that applies to Sauerbraten.