I was taught the cardinal rule about kidnapping: The more seconds that elapse, the more certain your demise.
If you have not made your move to escape before you are in the trunk, your chances of survival asymptotically approach ZERO.
Yes, NEVER get in the car. Fall to the ground, become dead weight, pee your pants, poop your pants, bite their nose clear off their face, shout obscenities, act like a crazed maniac,
stick your fingers in their eyes to the back of their skull, etc. etc....
Practice these techniques with your kids. Even a toddler can bang their forehead against the forehead of an attacker.
Don't worry about fancy self defense moves:
Look around and grab whatever is on hand...
a lamp---bash it over their head
a knife---use it in the heart and twist
the lid to the back of the toilet----bash it over their head
Do not freak out and whimper
Get into the mindset of a crazed ninja warrior and use what is available to you
take your car keys and jam them into their eyeballs
and prepare yourself for blood squirting.
Keep a rock that is long in your car or next to your bed
and grab that and bang it against the temple of their head.
What else do you have in your surroundings?
Think like a survivor!
This comes from training as a bank employee ( and we really did have bank robberies) and as a flight attendant (and we really did have hijacking attempts).