My sister and I were driving up highway 63 on a rainy day with few other cars on the roads. We were in the left hand lane (the "fast lane") of the 2-lane side of the highway headed north, and there was this somewhat older small white pickup truck (like a Toyota Tacoma) to our right in the other lane. We were between the two exits of the highway with no side roads to turn on to--only trees and grass--and my sister was needing to merge over into the right-hand lane so we could get off at the next exit. The truck wasn't adjusting it's speed to allow us over, so my sister had to speed up to get around it so we could merge in front of it into that lane. It was raining pretty hard and, like I said, they weren't allowing us over, so we were both really paying attention to the truck and our surroundings so we wouldn't get in an accident. As she's just ahead of the truck to merge over in front of it, we both glance forward at the road ahead, and when we glanced back over to merge, the white truck was just gone. Like I said, we were between exits with nowhere else to turn off, and the spot we were at has a hill of trees going up from the shoulder of the road so if the truck had gotten in an accident we would have been able to clearly see it, but the truck wasn't there anymore. The whole energy before that was already weird to us before that happened. We've thought about it being a ghost truck or something, but we really wonder if it was more of like some kind of time slip or something, I don't know.