He pulled in the driveway as I was finishing fixing the car
What happened after that?
I was scared and dropped the screwdriver.
It was unfortunate he scared you. It is good that you were not hurt and that you can finish fixing the car now.
I was thinking about how good it'd be to rip his throat out after scaring me.
That is an overblown reaction to what happened to you. I am sure he did not mean to scare you. You can still finish what you were supposed to do.