Exercises I can do in the car?

My family is going "dinosaur hunting" in Colorado, which is a good 10-12 hour drive.  I was wanting a good resource for some isometric or other exercises I could do in the car (or not look absurd doing in a gas station parking lot) just to keep the blood flowing to my legs.  I've done heel raises in the past.

Thanks for any ideas/suggestions!

Raise your heels to work your calves. With a stack of magazines, or a heavy Sunday paper on your lap for resistance, plant the balls of your feet, lift your heels from the ground, then lower them. Try toe raises, too. With your heels on the ground, lift your toes upward. Either hold them in place or raise and lower them. Work those thighs with leg extensions. Placing your feet underneath the seat in front of you for resistance, try to lift your legs as you contract (squeeze) the muscles of your thighs. This can also work without a seat in front of you. Simply extend your legs forward and hold for 3 count then repeat 15. Lean forward as though you're going to get out of your seat. When your rear end is barely off the seat, hold that position. See how long you can hold it, using only your arms for balance come back down and repeat 15. Strengthen your inner thighs. Place a pillow, blanket or small carry-on between your feet. Try to lift the item off the seat and squeeze your legs together at the same time. You can also place the blanket, pillow or other soft object between your knees and squeeze...again repeat 15. Burn those buns with a gluteal squeeze. While sitting, squeeze the muscles of your rear end. Hold, then relax repeat 15 Try and do at least 3 sets of each at 15 reps. Also, take advantage of the bathroom breaks...get out, stand by open car door, lightly rest hand on edge of door and do squats. Or, do some walking lunges across while at that rest stop. A loaded backpack on your back while doing the squats and lunges would be ideal. Who cares what people think...you'll more than likely never see them again!

Too true - they probably feel like doing the same thing anyway!  Thanks for the great ideas - I'll be sure to use them.

Curious what else I could do while seated, I did what I should have done to begin with:  I googled.  In addition to the above exercises, I found these, in case anyone else was interested:

http://www.ehow.com/how_17780_exercise-car.ht ml

http://www.washingtonpost.com/wp-dyn/content/ article/2006/08/14/AR2006081400879.html

Try moving ur ab area in and out like ur holding in ur breath and letting it out.  That will give u a good mid section work out.

squeeze your butt muscles... or do kegel exercises... you never know when that's going to come in handy...