Why does new battery work, but car will not start?

You have a parasitic draw, aka an electrical circuit in your vehicle is drawing amperage. I'd have a garage and or mechanic diagnose the vehicle to find the bad circuit.

2006 Mercedes ml350, change spark plugs and coils and new batteries, why is the engine running rough and shaking, 15 minutes the car shut down battery still good, is the engine bad or am I wasting money on it, somebody please help.