Well the GPS would be the part you add during the retrofit. It's not like they're that expensive anymore. Like someone1234 was saying, this seems like a problem

Well the GPS would be the part you add during the retrofit. It's not like they're that expensive anymore. Like someone1234 was saying, this seems like a problem that could be solved (at least as a prototype) by a smartphone app with a database of speed limits. Where's the complexity that makes that unfeasible?