There are two scenarios that owners report regarding the location of their car being wrong, or at least not what they expected.
This issue usually occurs after a software update and can also be accompanied by the incorrect time. It is related to a "feature" in that the cars position is only updated when the car is in drive and the wheels are moving. If you transported a car on a low loader, the reported position of the car would not update.
The issue is simply that the car has forgotten its last known location because of the software update or deep reset, and defaults back tot he place of manufacture.
The reason why it then does not automatically update on power up, is also the reason why the GPS location of the car on a tow truck doesn't update, its because the car only updates the location when the wheels are turning. This actually has implications for the GPS tracker as a security device as cars lifted and stolen will not report where they have been taken to until they are driven with a GPS signal picked up and a connection back to the mother ship to report their location. GPS receivers can also be fairly slow to determine their location when turned on in a new area.
The fix is really easy, and it's to simply drive the car for a few minutes. It should establish the location once it's worked out where it is, but as it may be a long way from where it thought it was this can take a few miles of driving. A secondary benefit is that the time in the car is updated from GPS and driving the car should also address any issues with that being incorrect.
This is a problem that largely only effects cars in Europe where Tesla adopt a European roaming SIM. On cars built with the old 3G module (up to late 2015), they had a Spanish SIM, and since then they had a Dutch one. As such any internet connectivity in the car through the built in SIM (i.e. not when tethered) will appear to originate from the home country of the SIM, e.g. Spain or Holland.
This was rarely an issue as the only time this was apparent was when using the web browser, and as that was so shockingly bad, very few people ever used it. With the latest change in Version 10 software, the web browser is being used more, regional content is more common and the 'issue' is becoming more apparent
There is no permanent fix, but web sites like google can have their settings forced to tell them both the country you wish them to assume you are in and the language you wish them to use, and this is easy to do.
For Google you can use the following basic structure to tell it what to do:
The website extension, in this case .co.uk can be replaced by the natural country extension of your choice. The hl=?? element is setting the language to use, en being English, de would be German, fr would be French etc. By using a combination of these two elements you can access Google for any country and in any language as the two are independently controlled. This can be especially convenient if you are travelling in a foreign country and need to find a local service, accepting that most of the web sites will still be in their local language. The trick also works on mobile phones.