This is a call that should be taken seriously. Car bombs are not particularly difficult to construct and, in crowded metropolitan areas, are difficult for police to detect ahead of time.
Car bombs have been used extensively for decades in Third World nations. The main obstacle here in the US is getting explosive material and detonation items. We saw with the attempted Times Square bombing a few years ago that this is not easy or straightforward. That car bomb fizzled due to technical mistakes made in its construction.
But we can’t depend on being lucky every time like we were in Times Square. If the Jihadis can build car bombs in places like Somalia, Yemen, Lebanon and Thailand, they can build them here.
Furthermore, the fact that Inspire is making this specific call should be treated as essentially a signal, a directive if you will, to Jihadis. History shows that one or a few will act on this call.
Where and, especially, when, is anyone’s guess. The Inspire article mentions New York, Washington, DC, northern Virginia, Chicago, Los Angeles. It mentions landmarks and sports stadiums as suitable targets, as well as major business facilities. The article also mentions the UK and France as targets for car bombs.
In the wake of this, don’t be surprised to see very strict enforcement of traffic and parking laws and regulations by US law enforcement–and don’t complain about it.