My girlfriend is a terrible driver.
Why do you think she's a terrible driver?
She yells at other drivers and frequently displays her frustrations with them while she drives.
You should be supportive of your partner. It's rude to say bad things about your partner and not be supportive of them. If you girlfriend struggles with driving, you could offer to give her some advice.
I'm considering taking her car away so that she won't be able to drive anymore.
It sounds like your partner really has some anger issues when she's driving. Taking her car away will only fuel her anger and make her resent you. You should explain how dangerous it can be to display anger when driving and help her stay calm and focused while driving.