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The Energy Policy Act of 2005 allowed for a national 400-pound exemption for the additional weight of idling reduction technology on heavy-duty vehicles. On October 1, 2012, Moving Ahead for Progress in the 21st Century (MAP-21) became law, increasing this weight allowance from 400 lb to 550 lb. Each state can adopt this exemption, at its own discretion. 

The map above shows how states recognize, or do not recognize, APU weight exemptions. Because laws and policies are subject to change, verifying them is recommended. If you have information about planned or enacted changes, please send a message to

For more information on Idle Reduction, read the National Idle Reduction Network Newsletter or see the Alternative Fuel Data Center's Idle Reduction page.  For more laws specific to idle reduction, see the Alternative Fuel Data Center's Laws and Incentives database.