awesome designs :)! and i second what oranghe said! longer bolder strokes! less hairy lines :> but honestly... the designs here are really refreshing to see!
The level design / world design of Dark Souls really is incredible. Combined with the atmosphere and challenge it made exploration so fresh and fun compared with other games.
there's a bunch of stuff on the zbrush site: http://pixologic.com/zclassroom/homeroom/lesson/vehicle-design/#car-design-part-2 it's all zbrush specific though.
are you trying to get a job as a level designer or an environment artist? a level designer would probably get away with it, an environment artist would be burned at the stake.