Denny Hamlin was fastest in Friday's rain-affected NASCAR practice session at Daytona, where most teams continued to focus on single-car testing, avoiding running in the draft.
The Joe Gibbs Racing driver, runner-up in the 2010 Sprint Cup series, was one of only 12 drivers who attempted running in the draft, although most of his slipstream mileage came in a two-car breakaway with his team-mates Kyle Busch and Joey Logano.
Hamlin set a fastest lap of 45.716 seconds at an average speed of 196.868mph, which improved on Thursday's top speeds set by the Michael Waltrip Racing duo of David Reutimann and Martin Truex Jr.
Tony Stewart was second fastest, also lapping in the 196mph range, and was followed on the timesheets by the Toyota of Logano, the Penske Dodge of Brad Keselowski and the Red Bull Camry of Brian Vickers, the latter completing the most laps of any driver during the day.
Once again the Earnhardt Childress Racing-powered Chevrolets showed great speed, with Richard Childress' Clint Bowyer and the Earnhardt Ganassi duo of Jamie McMurray and Juan Pablo Montoya being fastest among those focusing on single-car runs only.
Practice was delayed due to overnight and morning rain and it was after 1pm track before conditions allowed drivers to go on the track. The session was initially scheduled to run until 5 p.m., but officials extended running to 6 p.m. Although testing is scheduled until Saturday afternoon, many teams have already packed up to return to North Carolina, having completed their program during the first two days.
Reigning champion Jimmie Johnson, who was sixth-fastest of those running in the draft on Friday, will not be testing on the final day, and nor will his team-mate Dale Earnhardt Jr., who has family commitments on Saturday.
Following Saturday's sessions, teams will return to Daytona during the second week of February for the Budweiser Shootout and the Daytona 500.