you need a 'tuner' to receive the video signal - if that tuner is in your car, you will be able to watch 'over-the-air' channels - that is, the stations that broadcast their programming to antennas - so you'd get stations in your area
another way would be to use your home cable box tuner - this method would allow you to watch anything you could watch from home (dvr, etc) - you could watch it even when you travel beyond the signals that a tv station broadcasts - but it requires more equipment - and has more points of failure - it would work like this
1) cable tv signal to cable box connection - hardwired
2) cable box to slingbox (or a similar device) - hardwired
3) slingbox to internet router - hardwired
4) internet router to internet - hardwired
5) internet to cell phone - wireless
6) cell phone to car radio - probably hardwired though bluetooth MIGHT be possible
1-5 is simple enough - and i do it
step 6 might be a little more iffy - your radio has a composite a/v input - in theory the signal could be output from your cell phone into that input - but your cell phone probably does not have a composite output - so some conversion would be necessary, a cable might be able to do that (from a miniature hdmi (phone) to the 3 connections for the composite input on the radio) - then you'd need an 'app' on your cell phone to send the signal to the phone's hdmi port - then you'd need an 'app' on the radio to accept the signal on the composite input and display it - this is the weak point - i doubt there are any that will do that
however - some radios and cell phones are implementing something called 'mirrorlink' - in theory, your radio screen is exactly like your cell phone screen - and we know we have the ability to stream to the cell phone screen already (steps 1-5)
pioneer has some funky 'app radio' thing where IF the phone can support a pioneer supplied 'app', SOME functions are available on your radio (pandora and such)
streaming from your cable box is not cheap, though you might already have much of it in place - home internet connection (you'd be sending the data out so it should not be a metered service) - cell phone (smartphone) with an unlimited data plan - slingbox (or similar)
there might be something to 'apple tv' or your cell phone 'tv' apps - that would get the programming they offer to your phone, but you'd still need to get it to your radio somehow
streaming is nice though - you can control all the functions of your cable box and never again miss the season premier of honey boo boo
