1xxx are no more inaccurate than other automotive units of that era even with the modern larger more complex CNs. With all GPS automotive units you do need to be driving mentally a little ahead of yourself. It helps to also have a passenger-navigator to watch the GPS in a strange city of course, particularly in somewhere like Jakarta where the locals are all trying to kill each other and vying for 'the posthumous most-over-the-speed-limit title', but seriously at under 60 klicks unless you drove in the break-down lane it's a wonder you didn't end up as a heavy truck's hood ornament. ~100 m accuracy is appalling if your assessment is correct. Mostly 1xxx can achieve 15 m accuracy even in cloudy weather or with a few high buildings around.