I had one and the same nightmare in childhood (I dont know why but as a child I had nightmares quite often, but this one I saw almost every night): I saw myself sitting on a backseat of a car and the car was moving by itself - to be more exact there always was a driver when I got in there but then he disappeared. I know it may sound funny now, but back then it was not funny for me at all :( it was a horrible feeling. I was scared not as much of being crashed into something but more of the mystic fact that I was somehow trapped by a car and taken away somwhere far far away. After those dreams I could not stand a sight of a car in real life. Once my parents left me there alone for a few minutes and found me in hysterics later.

I have no idea why I saw this kind of dreams (I saw it a few times as an adult as well, but the feeling was different). It would be understandible if I had witnessed or been in a car crash but I`d never had. what is more surprising, recently I found out that my two younger sisters had exactly the same nightmare.
any ideas? :(

This is unrelated to your post but this is the second time I have read your post and both times I see the number 14, but there is no #14 to be found - unless I am over looking it. Is this of any significance to you because it irks me that I've seen it twice but it isn't there.

Now, on to your dream... For some children it is quite normal to have recurring nightmares with the same undertones. You were in a car with a stranger, you weren't afraid of crashing when the driver disappeared but you were afraid of being lost, trapped, and alone. Most children are afraid of mom and dad not being there, being lost, being alone and not knowing what to do. I had similar dreams when I was little. It's quite normal.  Your fear of vehicles came from the dreams and for no other reason. I hope you have overcome that now.

Thanks again for replying Angelique  
I got really curious about the numbers 14 u say u saw when reading my posts. I was trying to remember if they were linked to any special event in my life, but nothing comes to my mind.
and you say you saw them twice... inetersting