Never got to find out quite how big the load space really was in the end 
Here's how you could find out. A good project to fill the dismal days over Christmas.
Gather up all your wrapping paper, old newspapers and so on. Make up a bucket full of flour and water paste. Completely cover your new fridge freezer with paper, build it up in layers with the paste. Watch it dry (much more interesting than the TV Christmas specials).
Carefully cut a line up one side, over the top and down the other, remove your cast and tape the 2 halves back together.
Carry to car, and see if it would have fitted in or not, then you know for next time.
You can keep the cast to test out loasdpace in other cars that you might be replacing the SAAB with in years to come. Roll up at the showroom, take cast of fridge freezer from the SAAB and try it out in the whatever.