After any valiant effort to clean the car, I enforce strict rules. I announce that the dog is no longer allowed in the main area of the van, and whatever the kids bring in the van, they must bring out.
I'm a real stickler. For a few days. Then my kids break me.
Keep in mind one of my favorite ideas: We're not raising children; we're raising adults. While it may be easier in the short term to just clean up after your daughter, it's very important that she develop the sense of responsibility that comes from knowing she can sort out her own messes.