I've assembled the parts, the software (all free & not customized) and in a few hours had myself a functioning standalone Mode-S / ADS-B Mapping system on a 7" TFT screen.
This was built using a cheap RTL-Dongle, Raspberry Pi computer, and a 7" TFT Touchscreen display. If you wanted you could put this in a small enclosure and mount it in your car.
First came Car Radios, then Mobile Scanners, and now a Mobile Aircraft Radar System for your car!
You can see more about this project including a video here:
http://milaircomms.com/raspberry_pi_portable_aircraft_radar_system.html Enjoy
George
www.MilAirComms.com