Kazoo is correct. If you have reasonable grounds to believe you or yours will be seriously injured or killed, you have the right to use lethal force.

That said, you're in a multi thousand pound metal box, you don't need to mash the gas pedal down to the floor and do a burnout before running them all down while doing donuts. Put the car in gear, lay on the horn and start rolling forward slowly, gradually increasing speed but doing your best to not actually run someone over.