I have also been frustrated with keeping my seats and steering wheel looking new and matte. I posted on my a-ha moment with the magic eraser some time ago here: http://www.m3post.com/forums/showthread.php?t=389645
. I really don't think this topic comes up anywhere close to monthly...
Anyway it really does work miracles. I basically conceded a long debate in that post about the product being abrasive, it is, but it is very mildly abrasive. Heck, rub a soft shoe sole across a stone surface for hundreds of years and it is abrasive as well. More or less everything is abrasive, it is a matter of scale. Although I have heard the horror stories of complete destruction of leather with the magic eraser I think using it infrequently and very gently won't result in any total tragedy.
I've yet to see results from any product or technique that can make leather look as factory fresh as the magic eraser.