Same way they rate the other car escs I imagine- their own testing method based on FET ratings at a certain temperature. If you look on the CC website, none of the car escs have an official rating on their products page, for the afforementioned reasons Patrick stated. Back in the depths of time these ratings were discussed a bit more and people could look up the part # of the FETs to confirm how accurately rated the MMM was for example; underrated if anything, but allowing overhead is always a good thing
