If you're driving down the highway and you're running low on gas, there might not be a lot of reason to shop around before you refill your tank. But if you have a chance to ponder a bit about which errand you will fill up on, a company called GasBuddy has U.S. and Canadian prices - updated regularly by motorists - that will help you pick where to go.

This Gas Price Heat Map from GasBuddy shows gas prices within the last 48 hours in the Ann Arbor and Detroit area, color coded by zip code to show average price in the area. Data as of January 11, 2010.

GasBuddy.com

GasBuddy has a Internet-based user interface, plus a mobile version that works well on simple mobile phone browsers and an SMS interface (text "gasbuddy 48104" to 368266).

At the detail level, it shows you the price and last reported time at each station it has data for. It can give you a good idea of what the going price is, so that you can make a reasonable decision whether the place that's convenient and close by is also a good deal.

Edward Vielmetti's other vehicle is a half million dollar hybrid that runs on biodiesel. You can find him riding it at 5:03 p.m. at the Blake Transit Center, or reach him at edwardvielmetti@annarbor.com.