my vehicle serves 3 purposes:
- daily driver
- weekend 4x4 trail rig
- expedition style camping rig
so this isn't going to be your typical build, the things most people care about such as integrating into the dash or having a good audio/video system are the lowest on my priority list.
reasons for wanting a carputer, in order of priority:
1 - offroad navigation. handheld GPS have too small screens to use easily while driving offroad, the larger automotive GPS are too dumbed-down interface wise, and no pre packaged device can beat the flexibility of a true computer (like ability to run google earth and several topo mapping programs and a 3D routing app all at once and easily switch between them).
2 - documents/info repository. a full factory service manual is nearly 2 inches thick, not practical to have along for the ride all the time. but with a computer i can have the PDF of the service manual, parts manual, and copy down many informative car websites such as wjjeeps.com to view offline). i will also be able to pull up instantly trip plans and routes, scans of endless bulky paper maps, other peoples or past trail photos to compare to current conditions, etc.
3 - real-time vehicle/environment information display and logging. tying into OBD II and other custom sensors will provide great info on the health of the vehicle allowing less opportunity for problems to sneak up on you. breaking down 200 miles from anywhere in the middle of the desert sucks. having 100 gauges all over the dash sucks too. with a computer you can have endless virtual "gauges" and even store and graph trends.
i also have this vision of eventually creating a custom application that will parse logs from tons of sensors that i want and then stamp all my photos from the trip with what the conditions where when the photo was taken, such as temperature, GPS coordinates, elevation, etc. (based on correlating the time photo was taken with the log info). I may also tie video cameras into the system and record video from the trip and then be able to play back the video later in a custom app that plays back the logs in parallel so you can see all the vehicle and environmental conditions as the video plays.
4 - entertainment. currently i have the factory infinity soundsystem and it meets the needs of my non-discerning ears ok. i have an ipod integrated into the factory head unit and the factory steering wheel controls operate the radio and the ipod perfectly.
i do eventually want a dvd player in the mix with rear headrest monitors for the kid. i'm yet undecided whether i will fully replace the head unit with the carputer for all my entertainment needs, or just purchase an aftermarket deck with ipod integration and dvd playing capabilities. getting a carputer to work with am/fm, steering wheel controls, video, multiple monitors, and most of all startup and shutdown quickly is not an overnight project. for me the simplicity of an aftermarket headunit for all the entertainment needs may usurp my desire for a single integrated system.