What is the best equipment/way to record conversations in a car covertly?

I would suggest using the Sora Mivoice Pen Recorder:
http://store.yahoo.com/ahernstore/701p.html

It's a small, innocuous item that would blend in well in a car. The
sound quality in these is good enough to hear a conversation although
you definitely want to minimize other noise, especially rolled down
windows, but also stereos, AC, fans etc. If you do get external noise,
it is possible to to minimize this with a program like Cool Edit Pro
which you can get on Ebay or most software stores (the latest version
is actually now called Adobe Audition).

Hope this helps. 
-shiva777

---

Clarification of Answer by shiva777-ga on 30 Oct 2003 17:46 PST

I wanted to add that the pen can obviously be carried in a shirt
pocket making it even more innocuous. Also, if you need further
clarification, please ask before rating this answer. Thanks! -shiva777

Do you have free access to this car?

Yes, I have full access to the car