Study: GPS systems with real-time traffic can save drivers four days per year, cut emissions by 21%. Seems kinda high, but even if it’s double the real number that’s a big deal. I’m pretty sure that you couldn’t cut my commute enough to save that kind of time, though. . . .
UPDATE: Reader Kevin Murphy writes: “I have a GPS + Sirius Traffic Data in my Escape Hybrid. It’s fairly accurate if slightly delayed, but it lets me pick among my 3 routes to and from the office. It probably saves me 15 minutes a day in L.A., in my ‘mere’ 10 mile drive. Fifteen minutes a day over 200 days is 50 hours a year, so I cannot fault their numbers.”
Seeing how long commutes are one of the biggest factors decreasing personal happiness (more on this here), if you're a regular commuter investing in a traffic-enabled GPS could pay a handsome reward. This would allow you to generate fewer emissions and cut down on your fuel expenses too.