See this post here . It appears from the photos that it is likely the bomb was in the rear of the car.
Excellent! I claim no related expertise but it certainly appears to me that jeffers has nailed it. I kept looking at that same photo as I saw it on another thread and could not see any plausibility for a headrest explosion but I thought I might be missing something until I read the witness statement about the head being burned but intact — this certainly seems to have been a much bigger explosion in the back of the car, not what would have exploded from the headrest but merely burned the face/head...... but what do I know?