If your flying to US you have customs in AUH as opposed to when you land in America. Many people miss flights because of it so leave ample time.
you need to be a the airport 2 hours before the flight, for real. i missed my flight
+1
From my experience flying through AUH, customs/passport control on the way in was generally no more than 5 min (Except for me, who spent a half hour in an interrogation room, but that a whole 'nother story!), but on the way out to the US, you really do need those two hours. The lines are insane, and this was with me having Global Entry!
Figure with 14 hours on the ground, once you take out two hours back in AUH, at least 30 min dealing with rental car (between rental and return), and 2 hours r/t between the cities, you'll wind up with about 9 hours in Dubai.