Identify the total weight of shipments transported in 2016 by the newest Peterbilt.
transported in 2016 refers to CAST(ship_date as DATE) = 2016; 'Peterbilt' is the make; newest refers to Max(model_year)
SELECT SUM(T2.weight) FROM truck AS T1 INNER JOIN shipment AS T2 ON T1.truck_id = T2.truck_id WHERE T1.make = 'Peterbilt' AND STRFTIME('%Y', T2.ship_date) = '2016' ORDER BY T1.model_year DESC LIMIT 1