I am overwhelmed with the great suggestions!
Husband says no to a sewing machine in the car even if it is battery powered :-( I have a hand chain stitch one (reminds me of a stapler) that would work for Barbie clothes or small projects. I just have to figure out how to end without the stitches pulling out of the chain.
I have made dishcloths and afghans and even quilted hotpads in a car. I have not spent 2 days traveling though.
I tried out the White brand sewing mini in the store since the box was open. The bobbin thread did not pick up, nor did the fabric move with the feed dogs. I was curious about the Janome on sale at Hancocks though.
Thank you all for your ideas -- keep them coming. I have to keep myself occupied for a long long time.