Kyle Larson is the latest NASCAR Cup Series driver to be handed a stiff L1 penalty for having a noticeable indentation in the rear window after Saturday's KC Masterpiece 400 at Kansas. 

NASCAR announced Tuesday it found in the teardown of the No. 42 car the rear window was not flush to the rear deck lid and the rear window support braces were not keeping the rear window glass rigid in all directions.

An improper rear window with an ominous shape is believed to create an aerodynamically competitive advantage. 

Larson led 101 laps on the night and was in position for his first Cup Series win on 1.5-mile track but was involved in a dustup with Ryan Blaney with 20 laps to go. The contact resulted in a dented left rear and Larson told Fox Sports after the race the rear-window malfunction was caused from the incident. 

Larson finished fourth but as a result of the penalty, Larson's crew chief Chad Johnston was fined $50,000, and car chief David Bryant was suspended from the next two points-paying races. The team was also docked 20 points from the drivers’ and car owners’ standings and Larson will lose a playoff point earned with his stage win at Kansas. 

Rear-window penalties are nothing new for NASCAR this season. In March, Stewart-Haas Racing's No. 4 team of Kevin Harvick was handed an L1 penalty for two violations stemming from a rear-window malfunction on Harvick's Las Vegas race-winning car. 

Chase Elliott and Clint Bowyer also have all received post-race penalties this year for a lack of rigidity in the rear-window area. 

“The industry has kind of seen a rash of this type of thing lately with the rear windows,” Scott Miller, NASCAR vice president of competition, told “The teams have obviously found some performance in that area and they’re kind of pushing the envelope, not to say that anyone wants their stuff to come back looking like that and be illegal, but they’ve obviously found performance and they’re pushing the envelope, and when you do that, sometimes it pushes over the edge.

"I think that’s the case with this one and the case with the other ones we’ve had here recently with the rear window violations. It’s kind of more of the same.”