Summary

Quite difficult to use a Table car without opportune support.
I did this one that allow a simple bracket for the Land Rover Discovery 3 using the Vent Holes as fixing points and the plane below as support.
Please notice that the fixing position of the tablet with this support is inclined of round 30 degrees from vertical (parallel to the vent holes in that car above.

Instructions

The fixation on Vent Holes is using a sliding part one per side) kept in position with a small spring (size of the ball point pens).
The Fixing Plate need to be printed as per file and mirrored to obtain the two side: the two Fixing Plate are then kept together with two rod (I did used two M5 thread rods, length approximately 133 mm, to be fine tuned in place). I also put M5 nuts to fix them better.
Assemble all together, put the spring between the sliding hooks and the fixing pin (help them to slide using a small quantity of spray grease on the rails) and fix in place having the attention to left round 0.5 mm gap per side to allow an easy insertion of the tablet.
1st July: improved the sliding hook that is too small and difficult to stay in place with a bigger one.
Now it is composed by two pieces (A & B) glued together (and again they need to be printed as they are plus another couple mirrored for the other symmetrical side).
I slightly change also the Fixing Plate (the 'New' version) that have the back hook fillet reduced to increase the overall run of the sliding hooks).

SAMSUNG NOTE 10.1 2014 Edition - Car Vent Holes Support