You might be right, looking at the fire video, the burned out engine looks to have the Cats attached directly to the headers, which is how the LT6 is, but LT2 in the E-Ray has a different setup. It's really hard to tell in the burned out hulk, but any pictures around the front axle, or better pics of the burned out engine would be helpful. Wheels don't match any of the prototypes, so I am 50-50. There is no telling what could have caused this, but being a test vehicle, I am sure GM got some data. The smoke from the fire also does not look like lithium battery smoke, but just typical composite body and interior smoke.I believe GM already said no HV Electronics were in this vehicle and I also speculated it's actually the Euro Spec Z06.
I think the media jumped the gun on this one.