"most treacherous in the world" - that would be the Deerfoot 500, run twice daily, Mon-Fri. 
the Dakar you need a co pilot who reads the map which also has the terrains, I am not sure if this is the same race but there was one that in some parts of the race people had to go through creeks and rivers sometimes even building bridges out of logs or what ever materials were available.
hmm then I am way way off then , I remember watching a few videos on which I had thought was the Dakar and I swear there was a passenger that was basically telling the drivers what was coming up.Erm... no.. Thats different. Actually sounds like the Land Rover challenge or something similar. Where teams (usually about 3 crews in 4x4's per team) work to get through some truely horrendous terrain (literally through rain-forest the hard way)
Dakar doesn't HAVE to have a co-driver (or I suppose for the Dakar it would really be a navigator) as it's open to bikes as well but like any rally they do have them for the cars but they also race trucks too.. (Started out as the support vehicles)
hmm then I am way way off then , I remember watching a few videos on which I had thought was the Dakar and I swear there was a passenger that was basically telling the drivers what was coming up.
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