This happened 15 years ago.
We had been out for the day with the family. We were on our way home with my parents, sister and baby daughter in my van. As I had had a few drinks I asked my sister to drive and my wife and I sat in the back. We were both feeling extremely horny with very little action thanks to a young daughter and family staying with us.
I lay my head in my wife's lap and made it look like I was going to have a nap on the way home. I rested my hand under my head and quietly slipped my other hand up her skirt. She was sitting at the window so this was not visible to the others in the car. I could feel she was resisting me and was pressing her legs together. I left it for a few minutes and felt her release the tension in her thighs.
I took a chance and slipped my hand all the way up to her panty clad pussy. She was dying to stop me but unless she was prepared to give the game away there wasn't much she could do! I took my time rubbing my fingers up and down her slit, on top of her panties, and giving her clit some attention. I continued until I could feel her wetness begin to seep though her panties and onto my fingers. I could smell the lovely aroma of her pussy as she became aroused.
Now for the next stage! I slipped my fingers into the side of her panties and slipped them into her pussy. She was soaking wet and I lubed up my fingers and traced them up her slit until I found her clit. I started to gently strum her clit and rub gentle circles around it. I could feel that the reluctance she had shown earlier was now a distant memory and her hips were rotating and meeting my caress.
I could hear her breath becoming shorter and shorter. (thank goodness for the music on the radio!) It wasn't long before I felt her body stiffen and her orgasm washed over her. I could feel her wetness running over my fingers. I slipped my hand out and enjoyed the taste of her juicy pussy on my fingers.
Later that evening when we were dressing for bed I saw her panties and they were soaked through. Just what I love. I snagged them the following morning and enjoyed their beautiful scent while I shot a huge load.