Wanna know what you folks use in between washings. This morning I walked over to my car to find smudges, dirt, and fingerprints all over it

The culprit even wrote his initials on the car with his grimy greasy hands, my 8yr old nephew. The little shit gets no discipline from his parents, and because of that, anyhting I tell him goes out the window, doesn't even register. The only thing I had around was Windex, so I cleaned it up with that, and of course it takes off the wax. Any suggestions on what I should keep handy in the trunk?