What does the phones power level have to do with receiving a GPS signal? It is receiving, not transmitting anything. The satellites are doing the transmitting. All GPS units, be they in a phone or a Garmin/Tom Tom or a dongle on a laptop or in your car's nav system, are not transmitting anything. They are receivers only.I personally don't trust the phone GPS based on what I know to that extent. I'd try to borrow an actual GPS unit (Tom Tom or similar) to check against. You are running OEM size, and I'd have a hard time believing that your speedo is actually making you "speed" from the factory.
The GPS accuracy on phones is usually only within +/- 5m or something at best, and they reduce transmitting power in order to conserve battery.... a dedicated GPS unit will be much more accurate and reliable if you're trying to narrow things down to that kind of accuracy.
I understand the device uses more power if a GPS receiver is powered. That's understandable. High-precision using two will certainly consume more power. Power consumption is an issue in a device for sure. I thought your point was about it using more power to transmit something while in high(er) precision mode.Example
Consider cost vs rewards, including diminishing returns on investment, customer requirements, and implementation. There is no doubt that comparing position accuracy and tracking favors dual band GPS receivers. There are more points of reference and overall better tech thus better results...forums.macrumors.com