
You knew what I was going to ask!
But posting "learning/experimental" shots is very much part of the learning process. I do it. So do photographers much, much better than I am. We all are trying to see whether we're seeing stuff in a way that relates to other people.
In this case, there are at least three possible interpretations:
1) you were panning for the car up ahead (as Qveon suggested), the car's motion being the subject, or
2) you were just letting the light blurs to show YOUR motion, or
3) you pressed the shutter button while looking/feeling out the apple that you dropped on the floor.
If the last, please hand in your camera and go to the nearest driving school for remedial lessons. (

)
What you're discovering here is that motion (in form of blur) can be a very important story-telling technique. Depending on what your focal point is for the pan, you'll communicate different meanings. For instance panning on the car would have the car more or less sharp, with everything else (including your own car) be blurred. Panning a stationary point alongside the road will also convey the feeling of speed, but in a different way. Or you can complete eliminate the pan and let your own motion create the light trails.
At this stage, just play a lot. Try to have a purpose to each experiment, and make notes (if possible) about what you were hoping to achieve, what you did to do that, how it looked, and what you would do differently to improve on the results you got. And when taking pictures from moving cars, be in the passenger seat. Less grey hair all around that way.