Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_50 ( engine_capacity VARCHAR, model VARCHAR, mpg_us_extra_urban VARCHAR, transmission VARCHAR, mpg_us_urban VARCHAR )

### Question ###
What is the total engine capacity of the a4 transmission, which has an urban mpg-US greater than 19, an mpg-us extra-urban greater than 38.6, and an aveo model?

### Accurate SQL ###

SELECT COUNT(engine_capacity) FROM table_name_50 WHERE transmission = "a4" AND mpg_us_urban > 19 AND mpg_us_extra_urban > 38.6 AND model = "aveo"