How can I stop moving vehicles without having to chase it down?

I've found that the best way to get anything done easily in Far Cry 5 is to use one of the helicopters with mounted 50cal guns. It takes a bit of getting used to, but you can very accurately target anything and they are extremely powerful weapons. Plus you don't need to run anywhere, you can just fly!

With this method, you can decide whether to completely destroy any vehicle (very quickly and easily) or retrieve it to use yourself. If you find a vehicle that you would like to drive/salvage, simply kill the driver and either fly to where it stops, or shoot at it's tires and it should slow the vehicle down for you.

The best way I've found is a secondary grenade launcher shot at the front of the vehicle. It blows the tires, and disables the engine.

This tends to cause the vehicle to stop immediately, and doesn't kill hostages*.

Of course this won't work if you want to salvage the vehicle, and don't have a repair torch. This also won't necessarily work if you have the perk that deals extra damage to vehicles. It might just cause vehicles to immediately explode. I don't have the perk, so I haven't tested it in that scenario.

* When I posted this answer, I hadn't killed any hostages using this method. After using it like a hundred times now though, I did once accidentally blow up a hostage van, killing the hostages. The van blew up as soon as the grenade hit it, so it must have been in a fight before it got to me.