Well, I think they wouldnt void it but call them up to check
just to be safe. Warranty usually covers the engine parts
only.
Appolo_sg, while you are right that grounding help to improve the
electrical distribution, however, it also help to improve on the
electrical flow and stability, if high quality electrical cabling
are used. This also means less resistance at connectors of body,
engine and transmission. Grounding also help increase low and
middle engine torque, which will also mean you dont have to step
hard on your accelerator, thus, indirectly saves you
fuel.