It might be even easier than that. A lot of newer cars have a gas-saving feature where they automatically stop the engine when the car's stopped at a red light

It might be even easier than that. A lot of newer cars have a gas-saving feature where they automatically stop the engine when the car's stopped at a red light, and automatically start it again when you take your foot off the gas pedal. If you've got a car like that, then every traffic signal could be an opportunity for your car to be disabled.