Instrument cluster
 

When i bought my hhr used the instrument cluster i.e. speedometer readout was faulty and had been replaced by the used car dealership. The vehicle actually has 128k (now) but the readout says 80518...is there a way to get this readout corrected?

Find a shop with a Tech2 scanner , the odometer is vin specific and needs to be vin matched to the BCM

The odometer data is stored in the BCM. You odometer readout is probably not updating until the VIN matching gets done. The place that replaced the cluster should have done it, part of the job.

So I could go to the gm dealership or something? Or could someone at autozone do it? There's no codes or check engine lights

If the GM dealership will programme it, sure, it ain’t gonna be cheap!

They usually charge 1 hour labor if they have a technician that can do it. Most don't.