<<Hill Start Assist only keeps the car from rolling back for about 1-2 seconds when starting on a hill. It does not keep the brakes engaged however long you may require. You HAVE to get moving within that brief period otherwise you will roll back.>>

My W204 C-Class has Hill Start Assist, not Hold function. Pity.

Not sure what hold function you have on the W204. I have a W211 ('08 no SBC) and a W204 both 7G-Tronic. On the 211 I depress the brake pedal as soon as I release it (think of it as a mouse double click, only slower) and the HOLD braking is applied, HOLD is displayed on the Instrument Cluster Display and the brakes are only released when you either hit the gas pedal or shift to P. On the C there is no hold function, there is Hill Start Assist which AUTOMATICALLY keeps the brakes applied for 3 seconds after you release them while on an incline. There is no way to activate this function manually while not on an incline and there is no way to prolong the 3-second window.

thanks for clarification tmehanna, i was quite sure there wasn't any HOLD function since i remember asking the dealership beforehand, but wasn't familiar with the merc names for all its gadgets