I am not putting a lot of effort into the interior of the 2002 yet, but the stock seats were simply unusable. Many miles and some years parked in the desert had pretty much destroyed them. They were uncomfortable, and probably a dusty, moldy health hazard.
I picked up a set of used, but never installed, sport seats locally on ebay for about $100. These are made by 3A. They are basically the kind of thing you get from PepBoys for $250 or $300. They are pretty good looking and seem like a quality seat. They weigh about 35 lbs each which is the same as the stock seats, so I am not saving any weight. I would like to buy a more quality set of racing seats someday, but these should work fine.
The seats came with rails. The mounting width of the seats is narrower than the stock rails, but only by about 1.5 inches. That means that they would not simply mount to the existing rails and that attempts to center them on some flat stock would interfere with the car's brackets. I decided to use the stock seat rails because they seem stronger than the aftermarket rails and because I like to use stock parts where I can. I obtained two 1/8″x3″x18.75″ pieces of steel for each side to run between each stock seat rail. I then offset the seats toward the center of the car so that the inner set of seat bolts go through the stock center rail and the steel plates. The outer seat bolts go through holes in the steel plate. The plate is then bolted to the stock seat rails on the outboard side. There is an FAQ that is very helpful at BMW2002FAQ.
The outboard side is visible. A scrap of carpet or something can cover that.
As you can see these seats definitely look better. They put the occupant at about the same height as the stock seats, but provide a lot more lateral support.
The project took me about six or seven hours spread over a few days. Most of that was measuring and drilling holes.
The seats seem comfortable. We'll see how they feel on a long trip with the new Stage II springs and Sport shocks.