In normal circumstances, this would be easy. Just look at the base rate of deaths and see how the needle moved after these were introduced. This is how we kno

In normal circumstances, this would be easy. Just look at the base rate of deaths and see how the needle moved after these were introduced. This is how we know, for example, that automatic emergency brakes are saving lives. Unfortunately, the pandemic through normal out the window. :( Probably still possible to find some natural experiments where you can control some variables. My gut would be that their are some comparable cities that differ mainly in whether they have these cars. That said, it will be a lot harder, as the impact of the pandemic was pretty massive.