Welcome to the Quilting Board!
When I went to look at a featherweight for sale we met the seller in a parking lot and we hooked up a portable plug and tried it out in his van. Worked like a charm.I bought it
I used to sew while my husband drove in our RV. We had an inverter and i put my machine on the table with some anti slip under it and sewed to my hearts content. Just don't try to iron unless you have a big enough inverter ask me how i know LOL.
please please please do not carry your machine in your car only in the trunk. it becomes a big flying bullet if in a accident. there is a young girl here who got hit in the head with her dads toolbox. it caused extensive damage. ther was an article in readers digest awhile back with warnings on loose objects in a car.