Short answer: somewhat.
Fair Oaks resident Oleg Kaganovich swears by his device.
He'll even set it to give directions to places he already knows.
"My wife makes fun of me for it, but I do," Kaganovich said. "Some of my family and friends roll their eyes (at) my amount of use of GPS."
And when I-5 closes to northbound traffic Friday, he's confident in the promise of his Acura TL's built-in system to guide him around the detour.
The problem is, while the Acura's system and others will find new routes to the airport, Chris Webber's restaurant in Natomas or to the Capitol, they can't tell you that right now cars are backed up for miles on Broadway, that Garden Highway is a nightmare or that there's a sock hop on Capitol Mall.
Consumer interest in the Global Positioning System has soared in recent years. According to a recent study, one in six U.S. adults has a device capable of triangulating his or her position. That number is expected to climb rapidly as more new vehicles come with GPS systems installed.
Meanwhile, hand-held models keep flying off store shelves.
High-end models offer voice prompts, connect to your cell phone, play your music, or can list points of interest along your route.
Systems offering real-time traffic updates rely on data given to them by local agencies.
In Sacramento, that information comes from the state Department of Transportation.
The agency collects real-time freeway speeds from hundreds of sensors in roadway surfaces.
The department sends traffic information to your Garmin, TomTom or Magellan.
It's also posted on various traffic Web sites, including www.sacbee.com/traffic.
Surface streets might remain a mystery to many devices, however, since the city and county of Sacramento don't feed street data to the network.
"The data that is presented to the user is only as good as the data presented to us," said Nebo Nedeljkovic, the service-line manager for General Motors' OnStar system.
OnStar started primarily as an emergency service for GM drivers but has morphed into a full-fledged navigation system.
Nedeljkovic said OnStar users benefit from getting directions either by voice or through the car stereo from the service's central computers.
Rochelle Jenkins, a Caltrans spokeswoman, said the agency has been working hard to get the timing of all Big Fix closures to navigation system manufacturers.
"The three major ones are geared and ready to go," Jenkins said. "They will all detour their users."
Garmin spokesman Jake Jacobson said products getting traffic updates through an FM transmitter are ready for the Friday's closure.
"It will tell you when a traffic jam is happening on a highway, how best to avoid it, or whether the best route is to stick with the route even if you have a two-minute delay," Jacobson said.
TomTom's latest offer, the GO 930, allows users to gain from the experiences of others, as they report map updates or transmit actual traffic speeds either through a cell phone connection or by plugging into a computer.
