Although I can't convince hubby to skip the drive through, I can at least get him to turn off the engine when we have more than a 60-second wait. It uses less fuel to restart than to idle the engine. It helps the environment just a tiny bit, too.
And here's another one related to Deeli's: when you notice a red light ahead, ease up on the gas or take your foot off the pedal altogether. Your forward momentum won't slow down for several yards unless you're on an uphill grade. That's a tiny bit more gas saved and a tiny bit less smog to breathe, too.