it is true. I played around with it myself last week. If it comes through straight away and less than 5000 baht it does nit get flagged as international trsnsfer but just a bank to bank transfer instead.
Nakhon Phanom immigration insisted on 3 months before extension application. I was three days short and had to go back the following week. Always check with your own office.
Nakhon Phanom does not issue RC for anything to do with motor vehicles. I have to go to LTD and they request what they want from immigration. Takes about two weeks. Not saying your office is the same but ask at DLT. Dint forget the medical certificate, one for car and one for bike license. My copies were not accepted. Even though ink jets are pretty good they check for indentation on back! I've tried it but only got away with it once. Blue ink too on official forms.