Elliott topped the field with a lap of 157.363 mph. Johnson, an 11-time Dover winner, was next at 156.904 mph. They were followed by Kevin Harvick (156.897 mph), Kyle Larson (156.658) and Kyle Busch (156.631).
Austin Dillon had the slowest lap among the 16 playoff contenders. He ranked 30th of 38 cars that practiced with a top lap of 153.656 mph.
Busch had the best average over 10 consecutive laps at 155.518 mph. He was followed by Elliott (155.510 mph) and Denny Hamlin (155.049).
There were no incidents in the session.
Michael McDowell was forced the sit out the entire 55-minute session because his team failed inspection before qualifying four times Friday.