I enjoy hand quilting and embroidery. It helps me enjoy the trip. I try to have pieces ready to go for the out of towns.
As Brees123 said, Needle Turn Applique works well. I am one of those who can't sit still and has to be doing something. Glad God blessed me with that quality!!
It is all good!
Mariah

Jo from Joscountryjunction blog wrote that on car trips she removes the paper from paperpieced blocks. Maybe that would be something.

I had a top almost finished then decided I wanted to set it together differently so I have been unsewing in the car. Works great just make sure you have a cover for your seam ripper when not in use. I managed to stick mine in me and had blood spurting all over the place. I have gotten a lot of unsewing done though.

Strangely enough, I can't read in a car- not even a map for longer than 30 seconds or so. BUT I can sew. Just bagged two small charity quilts with thread to bind on an upcoming trip. I will also take a Lynette Anderson stitchery kit I have been working on for awhile.

I take projects to work on in the hotel room but during the ride I watch the scenery. I've watched a herd of cows put the run on a coyote, seen an eagle catch a fish in a river and watched herds of buffalo.

Lots of good ideas here. I finally finished my hexagons that I started EPP about 1996.... now the top is ready for hand quilting (but not in the car)....
I do basting onto freezer paper of pieces that will then be hand appliquéd.... working on the All About Bears quilt for the last little while.
I also have a simple hand embroidered project that I keep with me... usually all in one colour family so I don't have to worry about hauling my whole thread box.

Wool appliqué kits would be an idea because stitches are large. Or "cave man" stitching on a table runner or placemats since they can easily be held in your lap.

I have not tried doing hand work in the car. I have gotten carsick on trips since i was a toddler. The last time I tried hand work or reading left me with a terrible headache.

Hahaha, I meant I have a project to iron onto batik which I could then cut out on the ride.

I learned early on that my dear husband loves to drive and will very seldom let me do any driving. That was ok with me because I could sleep the whole trip and then sleep the whole night when we reached our destination. Fast forward 40+ years and I do very little sleeping. I have learned that I can read in a car. I also can crochet and knit hats on the hat looms. Try some of the suggestions that others have suggested and hopefully you will find something that works for you. Have a fun vacation.