I just used the internet site it said up to 14 miles off in accuracy on the results page. It was actually 4 miles off with my wifi off and GPS off and ZLAT off. I'm also pretty sure the location it picked is very close to an existing cell tower.
I tried location smart website said location accuracy was up to 14 miles off. They were really 4 miles off. So not that accurate. If it was 2 blocks like other poster I'd be worried.