[Chester B. Stone, Jr.]

Scott, I have a Rand-McNally 9910 which is designed to do what you want. However, the screen is hardly visible on a bright day, but I understand that their new model 9920 has improved the screen brightness. Also, Garmin has a new unit that will also do what you want (Garmin Diesel), but I cannot use it since it does not have an external antenna. I suggest you stop by a Camping World store to see the latest. I have not heard of any downloads for the Garmin nuvi to do what you want. Good luck.