Ah, this takes me back.
When I was younger (let's say, just out of high school <.< ), for a little while I had a fantastic lee. Her name was Sara, and she was by far the most tickling girl I had ever met til then. She really got into the whole bondage/tickling thing with me, and one night we agreed to meet super later to go for a session.
She snuck out around 1 am and met me outside, and I was driving at that time. I took her to a parking lot that was dark and secluded, and we got out of the car. As per my request, she had worn my favorite outfit - a one-piece black dress, black thigh highs, black heels, and no panties. I tied her wrists behind her back and sat her in the back seat on the passenger side. I blindfolded her and put duct tape over her mouth, then seatbelted her in nice and snug. I took off her heels and put her stockinged feet through the headrest of the front passenger seat, then tied her ankles together and to the headrest with a pair of neckties.
Now, before you all cry foul, I was young and had limited idea of what was safe and what was not when it comes to bondage. Fortunately everything went perfectly.
Anyway, without telling her what I was doing, we drove from the Blue Bell area of PA to Northeast Philadelphia, where we had some private space to have fun in. On the way, at every stop sign, I'd give her sexy little captive feet a tickle, and she's squeal through the duct tape. At red lights, I went to town, tickling the poor gal's stockinged soles like mad until it turned green. Twice, I stopped in a parking lot for an all night fast food place on Cheltenham Avenue and spent about fifteen minutes making her nearly cry from foot tickling.
When we finally got to our destination, she was really in for it - she wound up without her dress, tied tightly to the bed, and still blindfolded and gagged, while I fulfilled one of my biggest tickling fantasies on her - starting with her feet, I tickled up her body then back down, spending about half an hour torturing her, then making love with her while she was still bound and tickling her ribs at the same time. But that has nothing to do with tickling in a car, now does it?