depends on wht u want n wht u have
fitting it into a new model wont work , the new merce's have more advance standard ecu's
the old merce's arent plug n play to standalones , lots of work has to be done
so the question that i always ask , "wht have you done to the car that it needs a standalone"
if its stock , please keep the money bro :) its nt worthit to go thru all the hassle