An okay-type of big brother
I heard an announcement about this on the radio and decided to look it up - the Report a Smoking Vehicle program, which encourages people to report license numbers for vehicles giving off visible smoke. Their website is here. Summary is the program operates in the Bay Area only, where people call 1-800-EXHAUST to report vehicles (or they can report it on the web here. More than 10 seconds of visible smoke violates the required standard. An average of 35,000 calls are made each year, and apparently the owner of the offending vehicle gets a letter informing them they have been reported and may be breaking the law. A "high percentage" of reported owners supposedly return a form confirming the problem and stating that steps were taken to fix the problem.
In the modern Ashcroft Era, I'm not sure how enthusiastic I am about encouraging citizens to inform on each other. I think this one is more or less okay, however. The smoke is ten to fifteen times as polluting as normal car exhaust, and there's no question that air pollution is killing people. While I'm not completely happy about it, I think it's a good idea.