L.S.
Why make your life so hard. Get a portable DVD, it will work wonders. There is nothing wrong with it. They learn a LOT from cartoons/shows today. They usually are educational and lesson learning involved.
Personally, I watched tons of tv growing up, and it was not educational like they are today, and I turned out just fine.
It is up to you, but why put yourself and your babies life in jeopardy getting distracted while driving. I don't have it on all the time, maybe 20-30%, other times I sing or talk or give him some of his 100 toys I have in there.