human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: Season, Date, Winning Driver, Car #, Sponsor, Make, Team, Avg Speed, Margin of Victory
###Question: What was the average speed of Tony Stewart's winning Chevrolet Impala?
gpt
SELECT Avg Speed FROM table WHERE Winning Driver = tony stewart AND Make = chevrolet impala