Don't know about the C280, but many Asian models have a fuel flow fuse(controls fuel pump) that you first pull out. You then start the car and let it run until it dies out. This relieves pressure in fuel lines so that when you disconnect the fuel line from the fuel filter, your face isn't sprayed. You'd be amazed at the pressure that can build up in a fuel line.
I don't know what the ramifications are for pulling the ground strap off the battery on your car, but I always remove mine first when changing out the fuel filter.
Gas + a spark and you and your car are gone.
1991 300-SEL - Model 126
M103 - SOHC
James Madison - Oppressors can tyrannize only when they achieve a standing army, an enslaved press, and a disarmed populace.
Liberty Firearms Training - After years of trying to regulate California criminals with a never ending stream of gun control laws they have still not given up with the belief that if they make something a crime that criminals will miraculously start obeying the law.