The ONLY legal Vin is the one found usually on the drivers side dash or the drivers side door pillar and attached with "Rosette" rivets. It's an ISO spec 17 digit
ON the HHR it its on the dash seen thru the windshield
And since it is the only legal vin, that is the one the DMV, Insurance and cops use for VIN verification.
It is illegal for ANYONE other than a special law enforcement officer to alter that tag under special procedures.

It's totally legal to change anything else on the vehicle.
As far as mileage is concerned, after 10 years not needed and the Federal Mileage Disclosure has a spot for "mileage not actual" (Federal Law)

 

I have the Title for both cars, the Florida Car that runs like a top and is now like new we will never sell not a spec of rust. Took everything out of both cars from the wiring harness out of her 2.4 2006 to the steering column. Everything was cleaned and put back together and one push of the remote start button fired right up and runs like a top. Not a Single light on. Charged the AC and all is great! We are Registering the 2007 HHR from Florida that has been renewed and the other is heading to the scrap yard. I have a sparer HHR in my Garage attic now..lol

 

Love stories like this. Hope you stick around.