There was a youtube videoI saw once with a farm woman setting the tractor on its GPS autopilot & then she sewed while the tractor went down those loooonng rows. It would be difficult to sew in a car, but not impossible. I would get a half-size cookie sheet and as small a machine as you could find.
I have tried to do hand embroidery, but it was difficult. We were in our pickup pulling our trailer. It is not as smooth as you might think.