If I siphon gas from my neighbor’s tank while my car won't start, what offense am I committing?

Siphoning gas from a neighbor’s tank without permission constitutes theft, as it involves taking someone else's property with the intent to permanently deprive the owner of it. In this case, the correct offense is theft of property, which specifically relates to taking gas.

While the answer provided identifies burglary of a vehicle, this offense typically involves unlawfully entering a vehicle with the intent to commit a crime inside it, rather than extending to simply siphoning gas from the vehicle.

The situation described does not satisfy the criteria for burglary since entering the vehicle isn't a factor. Theft of service implies gaining services or benefits without payment, which is not applicable here. Criminal mischief deals with damage or destruction of property, which does not align with taking fuel, and grand larceny usually refers to the unlawful taking of property valued above a certain dollar amount, which would apply to theft of the gas but again does not fit as neatly as theft of property. The act of siphoning gas is more accurately labeled as theft of property.