interesting educational informal podcasts for long car drives?

i'm driving up to boston in about a week for work and it's like 5 and a half hours. i've been listening to a great podcast on the fall of the roman empire (the fall of rome podcast) but i only have one 40 minute episode available and i want other interesting stuff to listen to. ideally thematic, scholarly (tho informal/entertaining), and legit educational so not like this american life or freakonomics podcast even tho both have good episodes. like ideally i'd listen to a bunch of "the great courses" / the teaching company classes but sometimes they're pretty dry and they cost $$$ and podcasts are free. any recommendations? i'll take recommendations of stuff that doesn't totally fit this ideal too.

iTunes U in general:
http://itunes.stanford.edu/

CUNY lecture series:
http://www1.cuny.edu/mu/podcasts/category/cuny-lecture-series/

if u can deal w Dan Carlin, hardcore history can be good and the pods are often multi-hr multi-episode affairs. his style doesn't work for everybody but i have enjoyed a couple of his series (the eastern front ww2 cast and the ww1 series were good)

David Harvey on Marx's Capital, also the BBC's Philosophy series, and the Robert Schiller Yale financial markets course are all really interesting but perhaps dry.

iTunes U in general:
http://itunes.stanford.edu/

CUNY lecture series:
http://www1.cuny.edu/mu/podcasts/category/cuny-lecture-series/

overwhelming quantity. can u plz recommend specific lectures from them?

I often get those Great Courses and suchlike for free from a public library. Saved me from despair during a year of long commutes.

Lately on long car trips we've become partial to the Stuff You Missed in History, Stuff You Should Know, etc. type of podcast. May be lighter than what you were looking for but they are pretty easy to find.

which great courses did u like? i'm more willing to check them out than i sound above :p -- i have mcwhorter's story of human language waiting to be listened to

Ones I've listened to and would recommend...

Robert Caro:
http://www1.cuny.edu/mu/podcasts/2009/10/16/robert-caro-biographer-of-our-time/

Peter Gelb (short):
http://www1.cuny.edu/mu/podcasts/2008/06/25/peter-gelb-take-risks-to-succeed/

Looks like the Stanford one I was thinking of (Seymour Hersh) is gone.

In our time podcasts from BBC radio 4. Pick any you like the subject of.

Secret History of Hollywood has long 5 hour eps about Hitchcock, Warner Bros, Universal Horror, lots of good stuff. Well researched & very straight-ahead just the facts stuff, not too precious.

The History of Rome podcast started out great but the episodes around the end of the Third Punic War have a high pitched whine via Pocket Casts and I had to bail. I need to try with a different app to see if it's the files that Pocket Cast is downloading.

Seconding In Our Time , also A History of the World on 100 Objects.

I wanted to like the Stuff casts but I usually feel like they are just reading a wiki. They are just barely engaging enough to be good for falling asleep to though.