Championship 4 driver Kyle Busch was fastest in the first Cup Series practice for the Ford EcoBoost 400.
Busch posted a top speed of 172.695 mph around Homestead-Miami Speedway.
Truex and Harvick are among the Championship 4.
The fourth driver of the group, Brad Keselowski, was 21st fastest at 168.919 mph.
None of the championship drivers made more than seven laps in the session.
Larson had the best 10-lap average at 165.012 mph.
Dale Earnhardt Jr., who is making his last Cup start, was 14th fastest. Earnhardt will go to a backup engine after burning a piston early.
Matt Kenseth was 12th fastest.