You can use any pc and any windows based smart phone to watch and control your home tv from anywhere you have an internet connection. There are no fees other than buying the slingbox. I think this would be the simplest and cheapest way to get tv in your car. Also you will have all the channels from your home tv as well as anything you have on your DVR or anything else you have attached to your tv. I think this would be a great addition. Check out some of the sample videos on there website.
http://www.slingmedia.com/indexa.php
vidoes
http://www.slingmedia.com/us/extreme/