http://www.fco.gov.uk/en/travel-and-...ce-by-country/
Have a look at this before you get too excited about driving down.
Also, I would suggest a read of the Vehicle Dependant Expedition Guide by Tom Sheppard. You do need to be a pretty capable spannerman; at least that's my experience.
Mauritania and most of Mali are going to hell in a handcart at present
Morocco, along the coast, is generally OK but there have been some demonstrations that have been a bit hairy for Europeans
Travel down through Algeria is not possible at present. The main problem used to be robbers but I haven't been down through there for a few years
Since the Iraq / Afghanistan business travel in some countries has become very difficult
I hope that Libya settles down as I've always fancied an overland to Marble Arch and The Wire