Some tests with my dad's 2013 SL550.
I forgot to use my iPhone app for the tests... but I estimated the times using a stopwatch while watching the video playback.
1.) 4.2 seconds
2.) 4.6 seconds
3.) 4.5 seconds
The car has a 4.6L twin-turbo V8 producing 429hp and 516lb/ft of torque!