I can tell you that my carbon fiber cover reduces range greatly but never effects starting the car or unlocking when grabbing the door handle. My range to lock/unlock is only about 15ft max and with the cover off I can get 100 ft.

Not sure how carbon blocks it but it does somehow.

 

Some forms of carbon are conductive, super-conductive, or resistive. No idea about carbon fiber.

 

The more conductive, the more likely it is to interfere.

 

Yes, that's correct, carbon fiber can be an effective electromagnetic shield. It's not a great choice for a remote control case

 

Aw, bummer. I was thinking about getting a CF one, guesssnot...
Thanks for the heads up!