I won't defend CNN, because we know they wouldn't be consistent on this. If two white kids carjacked a black guy and killed him in the process, they'd be framing it as a murder and find a way to frame it as involving racial animus whether it was or wasn't. They are calling it an accident because they care about precision in their language.
However, there is a logical case to frame it as an accident. They clearly intended to steal the car, but they probably did not intend to kill the guy.
They're being charged with murder, but it's under the felony murder doctrine. Ordinarily, to be charged with murder, the prosection has to prove intent. However, if the homicide is committed in the course of committing another intentional, violent felony, the intent can be transferred from the violent felony to the homicide, making it a murder as opposed to manslaughter, criminally negligent homicide, etc.
So in the case of these idiots, they committed the carjacking, which obviously was done intentionally. In the course of doing that, they killed someone. It would be hard to prove that they intended to kill the guy, but the intent from the carjacking will transfer to the killing. Hence, they can be charged with murder. But in a vacuum, is it crazy to call the killing an "accident?" No. It probably was an accident, even if it's leading to a murder charge.
Just FYI - some commentators (liberal and libertarian) think the felony murder doctrine is unconstitutional. I'm undecided on the matter, but it's not a BS argument.