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Thanks for posting, the car can not operate on the gas engine alone for very long if at all. The gas engine is started by the hybrid battery through the motor generator, there is no starter as you may know, so if the HV battery completely depletes the engine can not start, the HV battery may not recharge and the HV computer will shut everything down if the battery goes below a certain level. Hope this answers your question and please let me know if there's anything else you may have concerns about.