Lot of automotive people aren't familiar with BMWs, then (and that's sad). Although I don't know how much longer they're going to be putting the inline 6 into cars. They seem to be switching over to the Turbo'd 4-pots, like everyone else is doing.
Packaging is a concern, nowadays - same reason we don't see the 360's base engine used any longer. 'Long hood / short deck' is a relic, these days.
Now it's just 'short hood / shorter deck (or 'no deck'; fastbacks are getting trendy again, IMO)
As far as the show where the staff seems to really know their business, does *very* good work, and doesn't seem too full of themselves - I kinda like 'Bitchin' Rides', which is Dave Kindig's shop in Salt Lake City. Best quality work on TV, IMO. The only downside is that they're 'full custom only', so if you like an occasional stock restoration, Dave ain't gonna be your builder. I couldn't bring myself to chop up a rare car, but they do it all the time on that show.