What is the epa rated combined fuel economy for the all-electric vehicle with dirty electric grid rocky mountains (denver) of 330 g/mi (205 g/km)?
create table table_23840623_4 (epa_rated_combined_fuel_economy varchar, operating_mode varchar, dirty_electric_grid_rocky_mountains__denver_ varchar, PRIMARY KEY (epa_rated_combined_fuel_economy))
select epa_rated_combined_fuel_economy from table_23840623_4 where operating_mode = "all-electric" and dirty_electric_grid_rocky_mountains__denver_ = "330 g/mi (205 g/km)"