There's a general guide for speeding fines in Germany, which was updated for 2016. The current fines?
These fines apply for any episode outside of city limits throughout all of Germany (local, state, federal road):
1-10 km over, 10 Euro fine
11-15 km over, 20 Euro fine
16-20 km over, 30 Euro fine
21-25 km over, 70 Euro fine,
26-30 km over, 80 Euro fine,
31-40 km over, 120 Euro fine,
41-50 km over, 160 Euro fine, 1 x months loss of license
51-60 km over, 240 Euro fine, 2 x months loss of license
61-70 km over, 440 Euro fine, 2 x months loss of license
Over 70 km past the speed limit? 600 Euro fine and 3 x months loss of license
When it says loss of license.....don't anticipate some sob-story or freaky explanation getting you off the hook. It's virtually impossible to avoid the fine or the loss of license. If your job heavily depends on you having a license....like a delivery guy? Your boss won't have any reason to help you out.