A number of states have imposed 3- or 5-minute  engine idling limits for trucks, with certain exemptions.
Three-minute idling restrictions
Three-minute idling restrictions are currently in force in Connecticut, Delaware, the District of Columbia, New Jersey and New York City.
Five-minute idling restrictions
Five-minute limits are now in force in Arizona, Colorado, Maryland, Massachusetts, Rhode Island, the state of New York, and now California as well.

In Texas, with certain exemptions, idling limits for trucks are five minutes per hour during the warmer months of April through October when truckers’ air conditioner use is heaviest. Other states have different versions of the rules but include more lenient time limits.
California Fines for Idling Trucks
The California Air Resources Board’s anti-idling rule carries fines starting from $100. It’s part of a wave of increasingly stringent regulations introduced across the country to help reduce greenhouse gas emissions, toxins and pollutants, and to save fuel.

The Environmental Protection Agency estimates that with a half million long-haul trucks now operating nationwide, wasteful engine idling may consume as much as 840 million gallons of diesel fuel a year.

For drivers resting in sleeper cabs, the rule poses special problems. Without use of their engines, they must rely on traditional deep cycle lead acid batteries, or small auxiliary diesel power plants (APUs) to provide overnight power for heaters, air conditioners, TVs, refrigerators, microwaves and other devices used when their cabs become hotel rooms.

Long-haul truckers who rely on batteries will experience continued daily reductions in battery run time and premature battery failure, since traditional lead acid batteries can’t tolerate the repetitive discharging required to achieve long battery run times.

Diesel-powered auxiliary power units consume up to 90% less fuel, generate some pollutants, and require long-term maintenance.