To increase the voltage from a 1.5V battery to power a small car, using a circuit from a disposable camera may not be effective, as it typically produces high voltage with low current for short durations. The discussion emphasizes that simply boosting voltage won't solve power requirements, as power output remains constant; thus, using a 1.5V motor is recommended. Concerns about gearing and weight are highlighted as more critical factors for performance than voltage multiplication. Suggestions include using low-loss gearing systems and exploring alternative battery types for better efficiency. The conversation ultimately advocates for sticking with the 1.5V battery while optimizing other aspects of the project.