The grilles pus out from behind. There are a number of curved, tapered leaf springs that expand against the rear of the grille opening that hold the grilles in. I have found that if you openthe hood and push outward on the lower edege of the grille that you can push it away just enought to get your fingers behind the back of the chrome rim of the grille to pull it out the rest of the way. A replacemtn grille set is around $50 at your BMW dealer, but I'll bet you can work out a trade here.