In case it's not obvious, that's a fat Buddha hanging out with two bobbing-head Snoopies on the carpeted dashboard of a taxi. In the Thai mind, there's nothing horribly incongruous about this arrangement.
It's a watercolor. I guess I cheated...the painting is based on a photo, which was then photoshopped, printed out, reproduced on tracing paper, and copied onto watercolor paper. From there, it's about as difficult as filling in a child's coloring book.