I've been reading the masturbation stories on this site for a couple of years and come back daily. I've never submitted a story before now. This happened just a few days ago.
I was travelling to a job-site (a trip I make 3 or 4 times a month). I take a short cut that knocks off 40 miles and is quicker. Last week I was making my usual 'potty stop' at a rest area along a major interstate highway only a mile before the exit at my short cut road. There was a young lady (late 20's to early 30's) fighting a large state map and obviously having trouble with it. As I walked by I asked if she was finding what she was looking for and she said, 'NO!'.
I asked where she was going and maybe I could help. She showed a point on the map that was beyond where I was going and the same short cut I usually take would apply to her. I told her I was going that way and she would be welcome to follow as long as she had enough gas to drive the 100 miles (or so) to her destination, she assured me she did. So, off we went.
The short cut is quite rural and much of it is unpaved, all of it is very scenic with lots of wildlife and even wild horses are occasionally seen.
When we arrived at the paved highway at the end of the short cut, I stopped and walked back to her car to explain where we were and which way she would need to go to find her destination.
She thanked me and thanked me and then thanked me some more and told me she was so grateful for the help. Her drivers side door was open and I stood near her so that my crotch was at face level to her. She asked if I didn't mind, she would like to reward me and pointed between my legs. Not knowing exactly what she had in mind, I told her she could if she wanted.
She proceeded to rub my, now quickly hardening, penis through my jeans as she slipped her other hand down her pants. Now totally hard, she unzipped my pants, pulled out my hard cock and began to slowly masturbate me while she resumed masturbating herself.
After only a few seconds, I told her I was going to cum soon. She turned me away from her and I shot my load all over the side of her car. As this was happening, she began to buck and moan as her own orgasm started.
After a moment (or two) of recovery, she leaned over, and gave me a kiss, thanked me again, closed the door and drove off!
I was left standing there with my penis out of my pants and beginning to stiffen again as what just happened began to soak in. I jacked off again, before resuming the drive to my work site. I've masturbated at least twice a day since then thinking of the event. I'll be sure to help other travellers in the future.