Mercedes has changed the Roadside Assistance policy. Basically if you haven't had service in the last year, no free service... even changing a dead battery.
So the solution is to have your car service by the dealer once in a while... Like some speacial deal for rotating tires for $40 or so... any special deals you like... and get it done so your car will be covered by Roadside Assistance.
There are some little details what is still free or not but one service done by dealer is better than AAA membership... which cost like $85 for preferred... and additional $50 per car. Yes, you can buy the basic AAA... but that is nowhere near what MB Roadside Assistance can do for your car.
Take advantage of factory roadside assistance where ever you can. Credit Card or AAA and other similar plans cost money... that doesn't pay unless you actually use it. Whereas a simple service at the dealer... you actually got something done and cover your car for a year... that is a deal!