Does anyone know on the latest tomtom one's 3rd edition onwards if you can upgrade the memory inside as they no longer have the sd cardson the bottom of them?

After much searching around the Internet I have only managed to find one link that may answer your question:

TomTom memory upgrade

Guy basically asks the same question - as there is no longer an SD slot can the internal memory be upgraded.

He answers his own post confirming no SD and says that after opening up his device he can see no way of internally upgrading the memory.

I expect it's going to be like a PDA inside, so the internal memory is hard-mounted on to the PCB and unless you have access to a Surface Mounter, a chip remover and the memory chips alone it will be a non-starter.

just an idea as it was cheap and my last sat nav had broken and i needed one fast for work that was cheap. never expect them to last more than a year, but i will look for a 730 next may/june time when they drop in price ready for the newer ones.