I made mine own. The bike sits vertically behind the car with fork
bolted/skewered to the bumper and the rear wheel tied to a profile
that bridges the rear window.

Cut two 15mm (OK, say 3/4") pieces from an L-profile,
drilled two holes in the bottom to bolt it to the bumper and one in the
vertical part to take bolts/axle for the fork with the front wheel 
removed. The rear wheel is tied with a toe-strap to a 50mm aluminum
C-profile that was fitted with a clamp like bent steel hook to be hooked
into the gutter. A bolt in the rear hatch 70mm below the window (I 
hesitated for three days until my brother took the drill) keeps the 
profile in place. The front wheel is strapped to the bike. 

The whole thing is absolutely bombproof (I had to realized that when
I backed up my bike into a rock), allows you to open the engine hatch
enough to get to the oil-stick and allows to open the rear hatch with
the bike removed. 

Send  $.02 for drawings in SASE, Jens.