I pulled the negative cable for 15+ minutes and so far so good. I'll keep an eye on it, but like I said in a previous post, it occaisonally is spot-on even w/o the reset. So I don't think it is the new map data, it's just the GPSM isn't updating properly. I've seen this happen only ONCE in the 3+ years I had the car before upgrading the tire sizes, and never again until now. The GPS is always very slow though, like it takes 1-3 seconds to update during fast turns or turns in the city. Driving around Detroit can be confusing because the GPS isn't updating nearly as fast, but my Samsung S5 is significantly faster with a smaller antenna. Heck, my Garmin Vivoactive can get a GPS lock in under 1 second in downtown during a race (Free Press, etc...)