How many dirty electric grid rocky mountains (denver) vehicles have an  epa rated combined fuel economy of 102 mpg-e (33kw-hrs/100mi)?
create table table_23840623_4 (dirty_electric_grid_rocky_mountains__denver_ varchar, epa_rated_combined_fuel_economy varchar, PRIMARY KEY (dirty_electric_grid_rocky_mountains__denver_))
select count(dirty_electric_grid_rocky_mountains__denver_) from table_23840623_4 where epa_rated_combined_fuel_economy = "102 mpg-e (33kw-hrs/100mi)"