I disable my 1990 300E 4 matic in the summer. You get better gas mileage, and it drives a little nicer, at least mine does. They are problematic, and really not even worth fixing if it goes out. Sometimes the cost is worth more than the car. On the earlier models like mine, you can disable. The newer ones, I believe 98 and newer, you cannot, at least there is no " test" valve for the system. Mine works great in the snow, but it is developing a little " chatter " when turning at low speeds. Shut it off and this goes away. BTW if you turn it off, in order to engage it again you MUST disconnect the battery terminal and reconnect it again. The light will " 4 matic light " will then go off. Good luck