I removed my back seat a while back to try and eliminate a rattle. I just left it out and drove around for a while. Guess what, both parts of the seat weigh nothing. Inconsequential weight. Without the seat you get more road noise which sucks. Also you can't throw things where the seat used to be because it'll slide around on the bare metal. I used electrical tape on the seat back hooks which quieted the rattle nicely.