Engine idling has long been a target of state and local legislators trying to limit it, and the trend appears to be continuing: Oregon implemented an anti-idling law this year, and California’s Air Resources Board won a waiver in February from the U.S. Environmental Protection Agency, allowing CARB to impose its own truck-idling requirements. For fleets that operate in many markets, keeping track of differing engine-idling regulations in different jurisdictions can make compliance a complicated affair.