NASCAR continues to work on adjusting aero packages and restrictor plate sizes, but speeds only went up on the second day of the series' Preseason Thunder test at Daytona International Speedway.
The sanctioning body announced it would trim restrictor plate sizes by 1/32nd of an inch to 29/32nds, and is also looking at closing the bottom of the cars' radiator grille opening and reduce radiator pressure by approximately four pounds.
Cars also ran in large packs of 10 or 20 for some of Friday's running, as was normal at restrictor plate races before the “two-car tango” took off in frequency. Still, it was the tandem packs that produced record speeds on Friday.
When all was completed, 28 of the 32 cars entered ran laps faster than 200mph, with Kurt Busch and Regan Smith 1-2 on the charts with fastest laps of 206.058 and 206.053 in a tandem, respectively. Both are in Chevrolets for Phoenix Racing and Furniture Row Racing. Chevrolet and Toyota teams locked out the top 10, with the fastest Dodge 11th (Brad Keselowski) and fastest Ford 18th (Ricky Stenhouse Jr.).
NASCAR's vice president of competition Robin Pemberton and Sprint Cup Series director John Darby are working on additional adjustments to keep the speeds down. Single-car runs should still hover in the 190mph range with the groups running quicker – either at or slightly over the 200mph barrier.