Don't mean to be a spoilsport, but sewing with a machine in a moving vehicle is courting disaster! If, heaven forbid, you are in an accident, the machine would become a "missile" and at the very least would cause you great bodily injury if not kill you. Anything not tied down in the car becomes airborne in an accident. The heavier the object, the more likely to cause injury or death. Also, think about what would happen if your airbag deployed...you would now have a sewing machine (no matter how small or light) buried in your face or chest. Not a pretty picture. Yes, I understand people use their machines in their RVs, but here again, if they are not secured to a table, they can also become airborne in an accident.
Sorry to be so graphic, but as a former EMT and ER worker, I've seen too many injuries/deaths caused by things "flying" in a car during an accident.
Anita