I've been using GPS for a while, and nothing has beat the update speed in my G35. If you can find a GPS reciever with a fast update speed, that's going to be the best one. The reason for this, is that the faster the updates, the more acurately the GPS software can make changes, alert you, and reroute you if needed. I have a spare reciever that updates 2 times every 3 seconds and it's FAR too slow. The one in the G35 updates 3 times a second. That's so much better. (It also seems to keep better track when going under tunnels and through covered parking lots.