The Canins Mesa is unique off-road vehicle that wasn't meant to be owned in the game. To obtain it, play the "The Wrap Up" mission where you will be given access to a Canins Mesa to escape a shootout. However, do not drive it on the road. Take a left down the hill to another road. There will be a helicopter chasing you but you can outrun it. You must reach Michael's four vehicle garage and park the Canins Mesa in the garage, then use a different vehicle to complete "The Wrap Up" mission. Once the Canins Mesa has been saved, you can also modify it.