When it comes to in-dash GPS units that are single din, the best way to go would be the Kenwood KVT-512 (around $550.00) slideout touchscreen with the Kenwood KNA-G510 (around $400.00) add-on nav. I have heard that Kenwood is soon to be releasing a sigle din slideout with the nav built in, but I haven't seen it yet. The Kenwood nav units are all Garmin based, so in my opinion they are the best out there as far as accuracy and ease of use. Another option that I have done a few times is to buy a dash bezel for newer style dash that has the double din opening, and with a little modification to the subdash it fits perfectly. This would allow you to use the Kenwood DNX-5120 (around $550.00) or higher models, and all of these have the nav built in, so there is no need for any additional equipment.