Short answer: NHRAWho said our cars are 10.00 NHRA approved
Longer answer: according to the NHRA rulebook, cars that are 2008 or newer that are unaltered don't have to have a roll bar at 11.49, which is what it is for other cars, like muscle cars and pre-2008 cars. You would still of course have to have a driveshaft safety loop, too.
They made this rule because newer cars are MUCH safer than older cars, and because the new mustangs, camaros, and dodges are fast enough stock to go low 11s, high 10s, and they probably figured that if they made all these people put roll bars in their cars, they wouldn't come to the track.
So, it's at 9.99 and/or 135+ that you need to add a roll cage. Roll bars and roll cages are not the same thing. A roll cage has a loop for the roof and bars in the front, and just a whole more.
Caveat: now your particular track may or may not let you run tens in your no roll bar hellcat. Each track can be more restrictive if they decide to. It's their choice.
Also, "unaltered" doesn't mean "unmodified." Unaltered means it's the stock type metal, interior, the air bags, all that sort of stuff, and the engine in the stock location, etc. They don't want someone rolling in with a gutted 2015 challenger and saying, "Hey, I don't need a roll bar or cage or anything", even though it's a stripped down race car.
I think I've read that some track told someone that unaltered meant any modifications, but that's not what "unaltered" is intended to mean. Before even buying our hellcat, I talked to the head NHRA tech inspector at my track to make sure that they would allow me to run to 6.40 (1/8 mile cut off) cause I didn't want to put a roll bar or cage in the car. I race at 5500 DA, and I am hoping for 6.70s next year, on 93 or VP110 if necessary. At my track if you start flirting with 6.40 they will make you cage the car. And there are a bunch of other requirements at that point too.