Definitely. Either, 3g, 4g/LTE, or Wifi. I've never had a need to check being unlimited so far but I don't believe it's uses a lot of data like streaming a movie does. I'm sure a google search will get you a better idea. I would suggest to use it only when you need it (i.e. know a portion of the route or on rt. XYZ for 50+ miles turn it off for a while).
if you are really worried about your data you could always do the search and get the directions already loaded when you are on wifi and setup the offline maps for the area(s) you will be in to limit your data usage.