There is an earlier thread on this
http://www.mybmwi3.com/forum/viewtopic.php?f=3&t=456&p=2974&hilit=Navigation#p2974
In particular somebody helpfully compliled a comparative list of functionality but there are a couple more things that contributors who have their cars may be able to comment on.
Firstly, is it the case that the functionality whereby the system tracks turns/speeds etc to continue provide nav when the satellite signal is lost is just on pro nav.
Similarly, somebody posted a copy of a document that was the 'handout' for a US workshop managers course which seemed to imply that some of the i nav functionality, such as range mapping and Eco routing is dynamic on the pro system but static on the business nav system. This may of course differ from country to country but it certainly isn't apparent from the official publicity material. This would be annoying for me as I've specified RTTI but not pro nav and the re-routing won't be much good if it is static and doesn't take account of RTTI.
The workshop managers' handout is under the battery warranty thread - http://www.mybmwi3.com/forum/viewtopic.php?f=2&t=530&p=6991&hilit=workshop#p6991
