Speedometer not working properly. Shows wrong speed while driving?
Might just be the speedometer head. If there’s a sensor problem, I’m seeing 3 different potential culprits. Some may be the same part, hard to say from the description. Vehicle speed sensor (VSS), transmission output shaft speed sensor, and wheel speed sensors. A shop would probably hook up a scan tool during a test drive and compare what the VSS is saying on the scan tool compared to what the speedometer is saying. How far off is it?
The vehicle needs a new instrument cluster.
Wrong size tires?
The speedometer head ass’y on this car apparently includes the fuel and temp gauge, tachometer, and odometer.