My Toyota Highlander hybrid '06 smells really bad while I'm driving it like burning wire or rubber what could that be

First make sure you're not overheating, hot coolant can smell like burning rubber. Then check you don't have any actual burning or melting wires, especially if you have added stereo components. You could check for an oil or hydraulic fluid leak, oil can splash or drip onto exhaust headers and cook off. Finally check for smells coming from the exhaust, catalytic converters can smell like rotten eggs when they start to go bad.

Did the original owner/asker of the question find a cause? I'm experiencing this symptom with my 06', particularly when under heavy load.