IL HB3721

Modifies the definition of "unattended motor vehicle" to exclude locked vehicles with running engines started by remote starter systems if located in municipalities with populations under 250,000.

Amends excessive idling regulations for diesel vehicles to allow remote starter system operation in municipalities with populations under 250,000, exempting them from the 10-minute idling limit.

Maintains strict 10-minute idling limits for diesel vehicles in the Chicago metropolitan area (Cook, DuPage, Lake, Kane, McHenry, Will, Madison, St. Clair, and Monroe counties plus specified townships) regardless of remote starter use.

Preserves existing exemptions for emergency vehicles, buses, vehicles with sleeping berths, temperature extremes below 32°F or above 80°F, and various commercial and utility operations.

Takes effect immediately upon becoming law.