Are you kidding? This has to be a joke, right? You can't possible be this dense.
What do you think the "420" represents? It's the size of the engine...in your case a 420 engine is a small V8 4.2 liter engine. A 560sl would have a 5.6 liter engine, and of course an SL550 would be........yes, a 5.5 liter engine.
The 2003 Mercedes-Benz M-Class has an engine horsepower of 215.
The 2011 Mercedes-Benz Sprinter's engine produces 188 hp @ 3800 rpm.
The 2013 Mercedes-Benz Sprinter's engine produces 188 hp @ 3800 rpm.
The 2012 Mercedes-Benz Sprinter's engine produces 188 hp @ 3800 rpm.
The 2014 Mercedes-Benz Sprinter's engine produces 161 hp @ 3800 rpm.
The 2010 Mercedes-Benz Sprinter's engine produces 188 hp @ 3800 rpm.
The 2012 Mercedes-Benz GL-Class's engine produces 210 hp @ 3400 rpm.
The 2001 Mercedes-Benz C-Class's engine produces 168 hp @ 5500 rpm.
The 2013 Mercedes-Benz E-Class's engine produces 302 hp @ 6500 rpm.
The 2009 Mercedes-Benz GL-Class's engine produces 210 hp @ 3800 rpm.
The 2013 Mercedes-Benz CLS-Class's engine produces 402 hp @ 5000 rpm.
The 2014 Mercedes-Benz M-Class's engine produces 302 hp @ 6500 rpm.