Only if the explosive has enough force to actually rupture the container. Putting gunpowder in a pipe works because the pipe lets the energy build up and then release in a single catastrophic burst. If the container is too strong for your explosion to break, you just contained the explosion. I have no idea if whatever he used would have actually caused much more damage in a regular car, though; my understanding was that it was mostly fireworks, which just don't have that much force (because they're not destructive devices).
Only if the explosive has enough force to actually rupture the container. Putting gunpowder in a pipe works because the pipe lets the energy build up and then release in a single catastrophic burst. If the container is too strong for your explosion to break, you just contained the explosion. I have no idea if whatever he used would have actually caused much more damage in a regular car, though; my understanding was that it was mostly fireworks, which just don't have that much force (because they're not destructive devices).