I know they twisted the story that Emma torched the car not Finn, but the very fact Finn didnt really blink when he realised it was Emma that did it was significant, I mean he in a sober state broke into a persons house and defiled it out of spite and jealousy.
TBH from real life experience the Police wouldnt want to get involved, straight in the books as a domestic with no human harm caused they would be off to eat their donuts.
With the police not prosecuting and no signs of breaking in on the car the result will be a huge NO from the insurance company and no further action from the Police.