MOORESVILLE, N.C. (July 28, 2016) – In an effort to further protect drivers, NASCAR today announced changes to its Sprint Cup and Xfinity Series cars that will race at Daytona and Talladega next season. In addition, the sanctioning body said the August race at Michigan International Speedway will feature the same aero package as at the first MIS race in June, with a few tweaks added to it. The aero rules, which were also tested at Kentucky Speedway earlier this month, are expected to be in place series-wide for 2017.

A rules bulletin issued to teams earlier today detailed the 2017 superspeedway changes, which have to do with the front firewall/foot box areas, the rear roll cage behind the driver and along the driver’s side door in the cockpit itself.

Anti-intrusion panels, which are already in place in those areas, will be thickened to add strength and to give teams more area on which to weld. The changes add overall strength to the driver’s compartment and will help limit movement inside during a crash. The driver’s head and neck are protected front-to-back by the HANS device or similar restraints, and the seat halo, the padded structure around the top of the seat, helps limit side-to-side movement. The changes announced Thursday help limit movement of the driver’s arms and legs during a crash and add support to the roll cage.

“We have a safety committee that’s been formed with a good cross-section of several teams,” said Gene Stefanyshyn, NASCAR’s Senior VP of Racing Development, during a press conference on Thursday. “Some have reworked chassis and some have built new chassis, so we make sure we have a package that is easy to implement. This is another round of enhancements to the overall safety of the vehicle, and we’ll be introducing it into the program, optional in 2016, mandatory in 2017 on superspeedways.”

The adjustments are essentially material changes, he said.

“We have in place materials; what we’re doing is replacing existing materials with materials which are thicker or are being formed with fewer welds. The way we attach some of it, we’re also creating, for lack of a better term, a zipper, so that we provide a lot more weld surface. We’re making the structure that encapsulates the driver more robust and manages energy in a better way.”

These changes are likely to be in place for all tracks in 2018, and development of other structures—seat brackets which deform, foam on the toe board inside the foot box and steering-column mounts—is under way.

At Michigan, set for Aug. 28, NASCAR officials decided on a final test of the provisional 2017 aero package, which is a low-downforce set of standards designed to enervate the racing and put the driver more in control of the racing.

The package will be essentially the same as that used in June at the Irish Hills oval. Similar rules were used at Charlotte (N.C.) Motor Speedway in May during the NASCAR Sprint All-Star Race and this month’s event at the newly paved Kentucky Speedway.

“We thought it would be a good thing to go back to Michigan with the Michigan 1 package,” Stefanyshn said. “There are several reasons for that. One, it would give us the ability to manage corner speeds better. There was some discussion of doing some tweaking on the package between Michigan 1 and Michigan 2. Where we all landed on that was, we thought it was best to proceed with the package we ran at Michigan 1 because the teams have some knowledge on that, and a lot of the teams believe they have some fine-tuning they can do on that package. This package relies more on mechanical grip than aerodynamic grip, and a lot of the teams think they still have a lot of things they can try. We thought it was best to prepare them.”

Given its spot on the schedule, Michigan was also a good choice because it doesn’t interfere with the post-season. “Michigan 2 is good because it is not in the Chase window and depending on what we see, it might give us the ability to do some fine-tuning if need be,” Stefanyshyn said. “The package for MIS 2 will be identical to MIS 1, and the tires will be the same also. Doing another race post MIS 2 is not in the plan. We want to keep the Chase clean and not introduce anything new.”

There are a few changes, including a 2.5-inch rear spoiler (down an inch from the previous package) and the removal of any rear-axle offset (skew). There are also modifications to the front splitter, cooling fans and the rear-deck fin.

Michigan’s 2-mile oval seems to be the test-bed of choice for NASCAR, as the sanctioning body tried a high-drag package in this race last year before switching to the low-downforce configuration for the June 2016 race. A four-team Goodyear tire test in May used the provisional 2017 package as well.