Can floor mat locks/tabs/holders or whatever they are called be added? If so, how do you secure them to the floor without worrying about water leaks?

Yes, if you ask around at your dealer they will probably give you a set. I was talking to the parts guy, trying to find the part # for the floor locks by themselves, when another parts guy said "Oh the techs have bagfuls of them back in the service bays". They come with the BMW floormat sets, but most cars already have them installed so they just throw them in a pile.

These are the screw-in kind, not the twist-lock kind. It doesn't hurt the carpet; it is about 2 inches thick where you screw them in. I wanted a couple of sets for my E30s, which never had floor mat locks. I screwed the locks into the carpet, marked where the mat sits, then put the fuzzy side of some heavy duty Velcro on the underside of the mat.

You can add them to your e36. I got my new mats and installed them, easy. You will have to poke a tiny hole in the carpet in order for the locks to screw in. Other than that, cake.
Umm.. I dont think water will really get in there, its covered once you completely screw it in. Besides, like i said the whole is small.

this should probably be in the general e36 section

Thanks for the input!

Use some sheet metal screws and that expanding foam insulation under the screws to make sure its water proof.

Or just search.

I don't think it's anchored to the metal, just carpeting.
Can floor mat locks/tabs/holders or whatever they are called be added? If so, how do you secure them to the floor without worrying about water leaks?

You got that right!!!!

they are both anchored to carpet, thus its easier to remove the carpet in case wiring is taking place!!

When I first read the title, I thought there was a new trend of people going around and stealing floor mats. What has our society come to when not even the floor mats are safe? :)

When I first read the title, I thought there was a new trend of people going around and stealing floor mats. What has our society come to when not even the floor mats are safe? :)

:D