Body saws only have a throw of about 3/16-1/4", so they work great in tight quarters. They work great in places where you don't want to overcut with a wheel blade or need reach without too much throw on the blade movement, like with exhaust modifications or replacements.
I found a Blue Point body saw on the street when I was 13 years old. I had no idea what it was when I found it, because the blade was gone, but I knew better than to toss it. I didn't even have a compressor at the time. It was missing the blade guide and the air coupler, so it lived in the junk drawer at the house until I started getting into doing body work, about two years later. I still use it, today.