Idle Public Employees
With gasoline in the vicinity of $4.00 a gallon you probably don't leave your car idling for very long. When you're idling you're getting zero miles per gallon. That's why cars with so-called "stop-start" technology have become more common. Basically those cars shut off the engine whenever you're sitting still for more than a second or two, and then restart it when you need to accelerate again, as when you stop for a red light and it changes to green. The Honda CR-Z that I tested for The Truth About Cars is a mild hybrid with stop-start. It uses an electric motor that both provides engine assist and starts the engine up almost instantaneously when the stop-start system is engaged. The system works. I tried very hard to fake out the stop-start system but no matter how I tried, I could not get the car in gear without the stop-start system getting the engine running first. It works that fast - and it does save a significant amount of fuel.
Between technical solutions to the problem of vehicles wasting fuel idling in traffic and drivers shutting off their vehicles when they'll be sitting for a while, it's rarer and rarer to see cars and trucks just sitting there with their engines on. Well, that is, in the private sector. I do see cars and trucks idling these days but more often than not they are government vehicles driven by public employees who think nothing of wasting fuel since they aren't paying for that fuel themselves. In fact they see wasting taxpayers' money as a perk of their job.