I have a U.S. car and it has the indentation, it so deep that my extinguisher, which looks the same size as the one shown, is completely hidden when placed at the deepest part of the indentation.The one shown is sitting on the safety triangle and first aid kit and thus is on the sloped face which comes back to the face level of the ends.
You can see the red safety triangle case poking out from each end from under the fire extinguisher.
The black bands are strips of Velcro that hold the three items in place.add

@F4celess, it is a photo looking at this face from inside the trunk that I am after, any dimensions you can add would be very helpful.
Thank you for your efforts here and any help you can give me.
My extinguisher is just held down on the mat and it would be nice to have it handy like yours is.
Thanks again.