So yesterday I picked up my brand new 2015 Outlander Sport SE.

Just a quick question. The dealer showed me how to open the doors by pulling out the key from the fob if the batteries are dead. However, how would I start it?

 

Don't let the batteries get to that point.
When it's a little harder to unlock the doors with the fob, replace the batteries.
It costs about $3 for each installed - at Radio Shack.