When it comes to cars, and really any technology, I have found that people often have false pretenses based on rumours or what they heard through the grapevine. For me, one has been that turning off my car engine only to turn it back on again minutes later results in more fuel consumption than leaving the engine running for that period. This is essentially just not true.
I know this because Chrysler has just announced that will be equipping a select number of its models with an engine start/stop option. What this feature will do is turn your car's engine off when the vehicle is in a stopped position, and once the brake is released the engine will automatically turn back on. This option is expected to increase fuel economy by up to 5%.