Crash all the self-driving ambulances, crash all the gasoline tanker trucks, crash all the trucks that ferry containers out of ports. You might not kill many people today, but when there's no shipping and no ambulance service people will start dying.
If you wanted to really disrupt society you don't need this level of sophistication or a lot of cash. A few thousand $ and a couple of months preparation time would be more than enough. Keep in mind that destruction and creation are extremely asymmetrical when it comes to the level of effort required.
