I'd just let him take the car at that point. If he wanted to shoot the woman, he would've done it already. You wouldn't have the knowledge that he shot other people in the morning. And if you screw something up....hung up on the draw, malfunction, etc, you are going to die.
If there's more to it, like he tells you to get in the car and drive, then I'd take the chance and shoot. there's a high likelihood of dying in a kidnapping of strangers
You never know what you'll do as a situation unfolds.
Does he have the drop on you?
Does an opportunity present itself to draw your weapon and prevail?
Are you enabling an obviously dangerous person to continue on and hurt or kill someone else -- maybe your child or spouse?
How can you be sure he won't shoot you anyway, just because he's got nothing to lose already and he's planning on suicide by Cop?
There are multiple accounts of store clerks 100% cooperating with an armed robber, only to be shot and killed as the criminal was done and about to leave. No reason for it at all.
For all anyone knows, if someone is robbing you at gun point, they may not want to leave witnesses. if you're at your place of business, it could be a disgruntled customer or employee/former employee looking for payback.
Then there are the crazy people wanting to rack up a body count for poops and laughter.
If someone points a gun at me, I will assume they are planning to kill me. If not immediately, then before the encounter has ended.