I think almost all US spec E34's had heated mirrors. The confusion comes from the fact that nearly all of them seem to fail after 2-3 years and they're something like $70 each! Both of my "95 540's mirrors had failed and I replaced the driver's side and it now heats all the time as far as I can tell. To be honest I'm not going to bother with the passenger side because I notice the effect of the heating maybe 3 times a year even in snowy NY.