Reverse Polarity & Load Dump Protection (TVS)
If you have a voltage peak the TVS will clamp it by draining current. Since you don`t have a resistor your diode most likely will blow.
Find the current that you need and calculate the resistance and power for your circuit.
Check the maximum clamp voltage of you TVS. It should be lower than your regulator.
A couple of capacitors may help to filter some noise from alternator and spark plugs. They will work as a RC low pass filter.