Well, my commute is about 10 miles each way to work. Mornings start so early so I have only a few red lights, but I do catch my fair share on the way home.
The first 1 mile to the highway is all suburbs, so no stop/start there (even if I hit a random light, the engine isn't warm enough to meet the criteria for shutdown), then about 4 miles on the highway are all 55 mph, and then the next 4 miles are "very city" 35mph with lights all over. Usually it's so early they're all green, but I'll say I usually catch around 6-7 lights, for around a 4-5 minute wait. I've noticed with the timer that the lights are usually around 45 seconds from red to green. The last mile or two is again highway with a 40mph limit, and my job is right off of that road.
So, if it's a 20 minute commute, and I'm idling at a light for 5 minutes (for easy math), that's 25% of the time. Obviously this figure is skewed: the more time you spend on the highway, the less beneficial the stop/start technology is to you. If you spend more time on the city (say your commute is 15 miles through cities/suburbs with lights), then the stop/start will be even more beneficial to you.
Again if nothing else it just called attention to the idling I was doing and not realizing.
I truly hope the Forester e-Boxer is available when my lease is up! I think I'm a perfect candidate for a hybrid... my mpg on the highway portions is in the mid 30's according to the screen, not so much in the city segment!
Since I am leasing I am not concerned with the longevity of the system, I just care that it works now. And it does, flawlessly. Cars are becoming more and more computerized and complicated. I don't know if I can go back to "owning" one again. No matter how infrequently a part breaks, adding more parts into the system just increases your odds of something, sometime going tango uniform. And whether it's something as trivial as a sensor or something else, it just makes me (irrationally) mad. Leasing is my ticket out of that, even if I spend a couple bucks more a month. There's a price for my peace of mind.