Automobile GPS units,,just bought two different models,,,
I've had experience with the older TomToms - they are great GPS units. That was my brother in law's unit that I learned on.
I do not want to use my "hunting/exploring/fishing" Garmin RINO 530 since it gets a LOT of use during hunting season which is long here in Georgia. I just bought a windsheild mount and a Carbiner clip mount for it,,,and the windsheild mount is VERY nice IF I have to use the RINO for the car.
I purchased a TomTom ONE {$499} thru Sam's Club as I've had top results with any purchase from them. Used it for two months. It was SUPER,,BUT,,,it did have what I consider a flaw at least for my purposes which is driving all over Atlanta every day to several customer stops. I may know where the house IS,,,but I may NOT have had to navigate to it from where I may be AT~!
The TomTom ONE was off in it's estimate of "time to destination" calculations. A two hour trip would be predicted to be 2 hours and 54 minutes away. The Garmin RINO 530 I have [purchased City Navigator for it] would be only a few minutes off the actual time travelled.
That was not too big an issue for me. However the feature it would not perform for me that I really wanted was this: You can 'save' any waypoint,,as an address,,point of interest,,,,many ways to save a destination or favorite 'point'. ONE method of saving a 'point' is to save a "GPS Position" when you are THERE,,,and no address is known in the software's memory. So, if I entered a new subdivision not on the TomTom ONE's memory I SHOULD be able to save THAT LOCATION by saving the "GPS Position". I would be about a few hundred yards off the "known highway", being at a new house location that I wanted to save. I would do the "save GPS Position" procedure and the unit would claim to accept it to memory. I could even 'title' the new saved waypoint. However,,just to test, I could drive away,,back onto a highway a few miles away,,and then try to navigate back to the 'saved GPS Position". The unit would say "route not possible". The ONLY way the unit would save a "GPS Position",,was IF I were ON a known [to the units' software] address or highway. THEN it would recognize the position,,and succesfully navigate back to it from a distance. I believe it was saving an ADDRESS,,not an actual "GPS position".
Sam's was great,,they accepted the unit after almost 50 days with full refund. I then turned around and purchased the GARMIN 360 Automobile unit { about $565},,and have been VERY satisfied with it. Both units are VERY fast to 'recalculate' a route if you pass a turn. I would guess about 3 seconds.
The GARMIN 360 seems to be able to save a "location" wether or not I am on a known highway or off on a piece of property. I think GARMIN may have the better road/address/GPS locator ability,,at least from my experience it does.
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WARNING,,,once you get used to one,,,you won't WANT to do WITHOUT one!