my dog, she gets car queasy

[pinkfrog]

This is very odd to me. I have owned dogs all my life, only a couple have been uncomfortable in the car so I quit taking them.
This doggie is different...
She used to be just fine in the car. I took her 3-5 days a week to work with me. This is roughly a 15 - 20 minute jaunt through rush hour (lots of stop, go, and go slow). She would just sleep. I have also taken her for numerous trips camping (3.5 hour hiway road trips) and again she usually just slept.
This past may long weekend we took her camping in a different vehicle and she started a whole new trend for travel.
Now going to and from work this is how she travels,
she shakes, whines, groans, pants, (no drool) paces, lies down on her side with her back to me in the passenger seat and will whine long and slowly. It's like she is in pain. I have taken her to work more, I have taken her to work less? I have done nothing different with this commute since before the may long weekend, and she just isn't the same doggie in the car anymore.
Please help? Am I just torturing her by trying to get her car happy again?
She is a 4 year old Pom/Mexican Terrior cross. She eats before we travel, and she reacts normally once we arrive at work, no excess drinking or eliminating to indicate she is near death after the car trip.
The change in behavior has me baffled. (nothing at work has changed either, and she reacts like this going both ways so no fears at either destination)
I am stumped.