the 17's are slowing down your car - if you can live without them, you could replace them with some lightweight 15's. pero op kors mas maganda porma ng 17's.
the next thing to look at is the condition of the engine - proper tune, new fluids, etc.
after that, standard breathing mods would help - exhaust, intake - but not much. the Benz isn't really a go-fast car, and aftermarket parts tend to be very expensive.