To get parameters used in reports, use the command unit/get_report_settings:

svc=unit/get_report_settings&params={"itemId":<long>}

{
	"speed_limit":<uint>,			/* speed limit, km/h */
	"max_messages_interval":<uint>,		/* maximum interval between messages, seconds */
	"daily_engine_hours_rate":<uint>,	/* daily engine hours rate, hours */
	"urban_max_speed":<uint>,		/* urban speed limit, km/h */
	"mileage_coefficient":<uint>		/* mileage coefficient */
}