How much difference did the husband’s prayers for their collective safety make, and even the preservation of the vehicle, to the outcome?

The prevention of injury and a worse collision that could have totaled the vehicle was due to divine intervention through prayers from multiple sources, including his. So all can share in the relatively minor consequence being far, far, better than what could have happened. It is often not appreciated when the divine steps in to help things, because one has not experienced the outcome without the divine intervention. So it is hard to compare and appreciate the contrast, but we can assure you that prayers were being answered and this was the critical factor here to minimize the damage all around.