Pontiac Repair: 07 PONTIAC G6, pontiac g6, speed sensors

Question
WHEN IM DRIVING MY CAR WHEN IM STEPPING ON THE GAS MY SPEEDOMETER SAYS IM GOING 80MPH AND IM ACTUALLY ONLY GOING 30MPH. CAN IT BE A SENSOR, PLEASE DONT TELL ME ITS THE TRANNY.

Answer
does the car upshift poroperly though the gears? meaning it's not shifting soner then it should normally? If not then I doubt it's a speed sensor issue. This has the proper size tires on it? if just the speedo is acting up I would lean towards that but with out driving it with a scan tool on it to verify the vehicle speed VS the speedo it's just a guess. the anti-lock brakes can be used as a copmparison to the speedo as well with a scan tool the wheel speed sensors can be checked VS the speedo as well.