VIEWS: 415 2020 GMC Sierra 3.0L Diesel We hit the road for a 100-mile loop to find out exactly how efficient the 2020 GMC Sierra new 3.0-liter diesel can be. 2020 GMC Sierra 3.0L Diesel Gallery $1000 Muscle Truck Walk Around (454 SS) First Towing Drive! 2020 GMC Sierra 1500 3.0L Duramax Diesel