Drive-Throughs (or is it drive-thrus?)

The local St. Louis Bread Company, known in other markets as Panera's, is adding a drive-through window. This prompted me to wonder how many barrels of oil we would save a year if people weren't sitting in their idling cars waiting on this product or that. I shared this thought with Heather as I ate my bagel and she sipped her iced mocha. She pointed out to me that if we did away with all the drive-throughs people would just burn up whatever savings there might be by driving around the parking lot waiting for a parking place to open up next to the door.