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_72 (class VARCHAR, year VARCHAR, chassis VARCHAR)

### Question ###
Which class has a year prior to 2011 and audi r15 tdi as the chassis?

### Accurate SQL ###

SELECT class FROM table_name_72 WHERE year < 2011 AND chassis = "audi r15 tdi"