I just realized the other day that I was actually running obdgpslogger from a startup script that is being run by /etc/conf.d/local.start instead of udev. It's running obdgpslogger -m though. I completely forgot about the script that's been sitting there until I went digging for a few files. It's ok though since the script also keeps each db file in a separate directory instead of merging all trips in one huge db.
Probably better to use udev. That way you can hotplug after bootup without problem, and it links the chain of cause and effect correctly; obdgpslogger should be tied to your OBDII dongle plugging in, not your computer booting up