Which car mount are you hoping to use this with?
I think the reason why case manufacturers make their own proprietary mount is because they all have different ways and numbers of magnets in their cases to avoid interfering with wireless charging. Some have 3/4 magnets and I've seen some that have more.
The one I'd think might work is the Pitaka case - I've used it with the Evutec magnetic car mount and it holds just fine (this particular mount doesn't have wireless charging, but if it did I'm sure it would work).