Peugeot 508SW works great!
I have a GMC Envoy that fits everything- harp, stand, chair and gig bag. Love it! (I've also heard Subaru Outback works too)
Thanks for everyone's contributions to the conversation! A new article was started that include your thoughts, as well as those that commented on twitter: http://harp.wikia.com/wiki/Transporting_a_Pedal_Harp_by_Car Keep those ideas coming!