User blog comment:FairyRaven/Fairy Tail Chapter 429 & 430: Code Blue & Purification Ritual, Review and Commentary/@comment-109.66.34.228-20150420110342/@comment-112.205.74.111-20150420154225

FTGM is right. Same when Rogue rides the horse to save Frosch from being bumped by the vehicle. During the omake episode that Frosch tries to be independent (forgot the episode title though ._.) I guess the motion sickness thing applies only to their respective exceed companions which they treat as friends and not vehicles or the like.