Legal Question in Criminal Law in California

Sure, if you knew what they were going to do you're a co-conspirator. If not, not, but you might be arrested and charged anyway. Don't talk to cops.

If they can prove you knew what was going to happen with your car, then you can be charged just the same as the person who committed the murder directly. If you had no knowledge (or they can't prove you knew), then you're not technically not guilty...

But that may not be enough to stop them from looking at you as either a participant or an accessory.

If this is more than just a hypothetical situation and there's a murder investigation, you should be sitting down face to face with a local criminal defense attorney to discuss your options and how to best protect yourself. Do that BEFORE making any statements to the police.

You could be civilly liable if the murder was committed with the car, as the owner of the car. But you would not be criminally liable unless you knew or were part of a conspiracy.