Originally Posted by
DrIsotope
The idea of "lock it inside your car" is both ridiculous and frankly, off-topic. It does not even approach answering the OP's question, and offers absolutely nothing useful whatsoever. For all we know, the OP has a car too small to fit a bike inside, or even-- gasp-- a truck.
So to give an actual answer:
OK.....
Drill a hole in the rack and put a eye bolt through the hole, put one nut on tight, apply some JB Weld to the threads and then put a second nut on.
Get a cable and padlock large enough to make you feel warm and fuzzy. Run the cable through both wheels, the frame and use the padlock to to secure it to the eye bolt.
Any thief will need a battery operated cut off wheel to steal the bike.