E39's do not have heated steering wheels, however, you can modify the slip ring in the steering column and install an X5 heated wheel on the car. Many owners swap the wheels from season to season as they do not like the non sporty M5 heated wheel.
I was wondering if you could get Sport wheel recovered and install the X5 heating element? Then you need sort out a way to power/control the heated wheel. Maybe off the heated drivers seat?? Maybe off the switching center?
As for an M5 not being a good fit, you should reconsider that statement. If you could get a deal on a reasonable M5, you put some PM into in the beginning and it will treat you right. There have been documented cases of E39 M5's going almost 300k miles!!
Of course if they are seeing the rev limiter every stop light, do not expect that kind of lifespan.
Last edited by jfoj; 10-12-2012 at 10:04 PM.