Vector3 90 Degree Rotation?

So here I have a script that moves a model (0,0,-5) studs forward, then it stops. I am wanting to know how to add a 90 degree right and left rotation that rotates the whole model. How would I do that?

s = script
g = game.Workspace
Car = s.Parent.Parent.Car1
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wait(0)
Car.BodyVelocity.velocity = Vector3.new(0, 0, -5)
wait(6)
Car.BodyVelocity.velocity = Vector3.new(0,0,0)