I recently sold my 2005 X5 4.4i that had only 44k miles. Two weeks after the sale I was contacted by the purchaser that my X5 had an electrical fire caused by the cooling fan. Apparently the wiring to the fan shorted out causing the fire which spread to the fan shroud. The new owner of my X5 had just pulled into their attached garage containing other vehicles and a boat when the short occurred. Luckily the driver smelled smoke and was able to put the fire out. This could have been much worse.
This doesn’t appear to be a one-off incident, as 2001 X5’s were recalled for this problem (see link). A 2005 X5 caused a fire at a Winnipeg auto dealer apparently due to the same fan issue (see link to story).
I suggest that owners of the E53 X5 have their fan and supporting electrical circuits checked out to prevent this from happening again.
Used 2001 BMW X5 Recalls - 2001 BMW X5 Recall Reports - Motor Trend Magazine
BMW defect alleged in $450K Winnipeg fire - Manitoba - CBC News