Innate Attack (burning) VS. Car Gas tank

[Empada]

Hi, I have a player who want to use his telekinetic innate attack (burn, 1d) to set a car on fire, attacking the vehicle gas tank, and I'm not sure how to handle it.

for hitting the tank he has to see it or have some idea of where it is?

his attack has No Signature and I have no idea if the enemy can notice him doing the attacks.

also, where do I look how much damage is necessary to it start the fire or blown up the car?

thanks