328 bmw trim, what is leatherette?

That's about it—it's the standard vinyl interior. I've had several E46 BMW's with leatherette interiors. Leatherette doesn't breathe as well as real leather and tends to be hot under your butt in the warmer months. My cars always have the Sport Package and the driver's seat bolster develops a crack after about 6-7 years.

Looks like you gents beat me to it. Nice sportwagen by the way. To clean it, some light soap and water works for most stains. You can always use a vinyl treatment, like Armor All, on the material for a shine. However, you might experience a bit of the old Slip n' Slide motion if you use too much.

I've found that Zymol Leather Cleaner/Conditioner works great on leatherette. You don't get the Slip n' Slide motion and the shine is more natural looking. Seems to keep the leatherette supple as well. Like your E39 wagon. I had an 01 sedan with a manual & loved it.