What is the most Champ Car wins for any driver with a USAC record of 2?
create table table_19524523_1 (champ_car_world_series__2004_2007_ integer, usac__1956_1995_ varchar, PRIMARY KEY (champ_car_world_series__2004_2007_))
select max(champ_car_world_series__2004_2007_) from table_19524523_1 where usac__1956_1995_ = 2