21. Mystery Twin-Turbo V6 GM Vehicle
The leaks that poured out of General Motors this year were worse than A$AP Rocky's album leaking a full month ahead of time. They couldn't really keep anything secret, and as a result, the auto industry got wind that a twin-turbo V6 is in the works for this year. It's purely speculation where this engine will end up, at this point, but it's only a matter of time before Cadillac launches an ATS-V. And dont' forget about that Buick Grand National rumor.