Strictly a matter of weight, not whether it's a BMW or a Yugo. I don't know the GCWR and tow ratings of his RV, but he needs to look them up and then compare to the BMW wight. A "small" BMW, e.g. a 318i, weighs in around 3000 lbs, so ought to be be towable with most any coach (assuming the BMW is towable at all).
Manual tranny BMWs are probably towable, but not automatics and maybe not the hybrid either.
Former owner of 2004 American Tradition
Home is in the Ocala Nat'l Forest near Ocala, FL