I'm about to purposefully purchase a new vehicle without the $2,000 nav option and plan to use my iPhone 4 instead. I've done my due diligence with Google trying to find a complete review of all the worthy apps that are available but can't seem to find anything newer than the 2nd half of last year when they just started to hit the market. Any input on which Nav app is best? Pros / Cons.. maybe even point me towards a review that I haven't found. Also, who's using the car kits made by the app company? Are they worth the extra $100?