What is the average edispl of the cars of model volvo?
SELECT avg(T2.edispl) FROM CAR_NAMES AS T1 JOIN CARS_DATA AS T2 ON T1.MakeId  =  T2.Id WHERE T1.Model  =  'volvo';
SELECT avg(T2.edispl) FROM CAR_NAMES AS T1 JOIN CARS_DATA AS T2 ON T1.MakeId  =  T2.Id WHERE T1.Model  =  'volvo';
[{'avg(T2.edispl)': 133.5}]