Get typical traffic for roads, not just highways on Google Maps
google-latlong.blogspot.com
google-latlong.blogspot.com
Instead of using the defined speed limit on each road to calculate how long it takes to travel it, they use the actual speed instead (for each 15 minute segment of the day).
It works really well, as long as I don't make any incorrect turns, I no longer sit in traffic.
Don't get the 550 instead, the 540 is much better.
If it's too large for you, the XL 340TM is identical in everything except screen size.
The other models have lots of other features (voice input, bluetooth, mp3 player), but they didn't seem worth the money to me.
The only drawback I've had with it is that it takes longer than I would like to recalculate a route if you miss a turn - especially if the destination is distant.
Also does the FM receiver work in most places? I'm pretty far away from any cities.
The traffic receiver will get you current conditions for the larger roads. It's pretty much only the roads that you'll hear mentioned during traffic segments on news radio. So if you have traffic on your local radio you'll probably have traffic from the receiver as well (you must also have a large FM station in your area since it piggybacks on that). It also includes all construction issues and lane restrictions/closures, even those not mentioned on the radio (I assume they get it from the municipality).
If you are far from cities I can't image you have much traffic - where it really shines is when you travel to a city. It will tell you "In 5 miles on the road you are on there is a slowdown to 20 mph lasting for 2 miles."
Due to bandwidth restrictions it's not super accurate on exactly where on the road the slowdown starts/ends but it's pretty good. The GPS unit will automatically recalculate your route to avoid the traffic if it can find a better way. Or you can have it avoid the traffic no matter if it thinks the alternate route is slower.
Thankfully they do support secondary roads. My Garmin GPS has a live traffic receiver but only has information on the highways and very major side roads. This means it can't make a decision about getting off the highway if there is a problem.
Google also unhelpfully do not make it possible to report map errors from with the Maps/Navigation app. They claim there is parking in the middle of a park near me which is definitely not the case.