You'll find many reviews and discussions about the JR Pass if you search. I think the most commonly purchased pass is the Ordinary pass that covers the whole country.

One type of pass that might interest you - if you want to keep the idea of a road trip alive - is a JR East pass. Unlike the whole country pass, you don't have to use it for seven consecutive days. It can be used for any five days within a 14 day period:
http://www.jreast.co.jp/e/eastpass/#category02

Now, you need to decide if you're most interested in the region covered by this pass - It includes vast areas of Northern Honshu that make for pleasant driving. It can also take you to Karuizawa and Kofu, mentioned in this thread. But it does not include the cultural triangle (Kyoto, Kobe, Nara) or some of the other famous cities that your friends might be thinking of (Hiroshima etc. )

And another type of discount ticket that might be attractive for a group that wants to drive (assuming the timing of your trip is right) is the Seishun 18 Kippu. It can be used for groups, but there are limitations on the trains you can use and the period of validity:
http://www.japan-guide.com/e/e2362.html