eatery is fed up with presidential candidates coming in with their entourages and disrupting the real customers. so colby's breakfast and lunch in portsmouth posted a side that reads in patriotic red, white and blue, "no politicians. no exceptions." the owner says no one has broken the rule since the sign went up. the federal government wants to clear the air coming from big rigs. correspondent claudia cowen reports on new regulations. those who like them and those who do not. >> for the first time, the federal government is regulating big rigs, r.v.s and tractor-trailers in much the same way as it's held car make torres rigorous fuel efficiency standards for decades. circumventing congress, the environmental protection agency is ordering heavy trucks to reduce green house gas emissions by 20%. overhaul engine design starting with models built in