Why Gas Vans?
The Nazi leaders knew that there was a strong impact on their soldiers when they had to shoot and kill the Jews, especially women and children. They wanted to find less stressful ways to get rid of the people they wanted to get rid of. This was one of the ideas that they came up with. They used these vans until gas chambers were made. These were a much more efficient way of exterminating the Jews.
How it works
They would put the Jews in the back of a van. The exhaust of a car usually leads through a pipe to the back, and out into the air. In the gas vans, they would lead the exhaust into the back of the van, where they had all of the Jews. This would give them carbon monoxide poisoning along with suffocation and cause them to die. This was happening while the van was driving to a hole or pit. Once there, they would dump in all of the dead bodies.
Different Types of Vans
In the pictures above, you can see that the vans are not huge. And they were meant to accommodate 30-100 Jews at time. To accomplish this, they were basically shoved in the van and crowded to as many as they could possibly fit. They were suffocating in this, and barely had room to move. It was pure evil.
One disadvantage is that this was not a super fast process. It took the Jews about 20-30 minutes to die in the back of the vans. And while they were back there, the drivers could hear them banging on the walls and screaming. So these drivers were driving around for about a half hour listening to the agonizing pains of dying people the entire time. This was disturbing for them and took a large toll. As a result, gas chambers began to arise and become more and more popular. Eventually becoming the main method of killing for the Jews.