if i remember correctly all private vehicle transfers are "as-is" unless other wise indicated. not sure there is much he can do. sympathize with his bad luck and dont worry too much.
6bangBronk can probably give you better advice.
I don't know??? Every case is different and you got nutcases out there now days so without being there??? But being that I have 100% positive feed on everything I've ever sold over the past 20+ years either from Craigslist, NC4x4, word of mouth or Ebay (Gittinwidit), I have had some instances that turned into learning experiences quick! Trick when selling is to be as honest as you can and explain ANYTHING you aren't 100% about before an item is sold. If something is said to be "as-is" there's nothing he can do?
What year was the Cherokee? I think the rule is anything 10 years or older can't be held up in any courts if defects are found when bought from a private individual? Unless there's something listed on the carfax report or it was bought with some kind of warrenty or you simply lied about something?
From what I've gathered, dude is simply SOL... And you can't always please everyone 100%. Try working as a server in a restaraunt sometime. There's always that 1% that will try to get something for nothing (There's a fly in my soup). I also only deal with cash / trade, or whatever currency that is turned into cash before an item I'm selling leaves my premisis, unless I'm the one towing / delivering. Once I got the cash and you have your item and everything is a done deal, my cash is said "spent". And you can't sue someone who has no money.
But I usually put a guarantee on anything that I sell that isn't electrical, motors or something with movable parts that is said to not be operating properly. Motors and electrical items are "wear" items and you're out of your mind to guarantee them if they are older than 10+ years unless it's just something you have 12+ others of just laying around. Heck, I'll take a $20-$30 anything back if it results in someone being happy. And I'll guarantee rear ends and transmissions for they are usually either good or not when they are sold.
I say, put the money in a drop box for 5-6 weeks if you're worried about it and carry on as money was "spent".