Here's what drives me crazy about auto stop/start systems....
Yes, we all know that idling for long periods is inefficient, and we should be more conscientious about turning the car off while waiting for our passenger to run into the store, or whatever, but when we are in traffic, the car's computers have no way of knowing in advance if we just stopped for a train that is going to take 8 minutes to pass, or if we stopped because of a slowdown on the freeway, and will be going again in 5 seconds. Starting an engine from a stopped state means overcoming the inertia of all the moving parts, and if you recall your physics classes, kinetic energy is exponential with speed, meaning that for short stops, getting an engine up to speed again will take more energy than it would to overcome the friction to keep it idling. How short? It depends on a lot of factors, but even without knowing the answer, the fact remains that the car's computers cannot see the future, and don't know how long we will be stopped, and so under some driving conditions it's entirely possible that the start/stop will be less efficient than keeping it running, and that's not even accounting for wear on the various components, or the extra vehicle weight incurred by the over-engineering required to beef up the starting system. It's a sad state of affairs when we no longer trust people to take responsibility for their own choices, and instead try to force choices on them that might not actually be helpful.