Lots of online mapping services tell people how to get someplace. A new Google Maps mashup, developed by Seattle-based Clarian Labs, also tells drivers how fast (or slow) they should drive along each leg of the route for maximum fuel efficiency — taking into account factors including traffic lights, speed limits and other local traffic conditions.

The free service, called EcoSpeed, is available now as an online demo.

Drivers who follow the recommended speeds could see a reduction of as much as a 30 percent in fuel usage, the company says.

Clarian Labs is planning to release the EcoSpeed as a free iPhone and Andoid app in time for the South by Southwest Interactive conference next month. A Windows Phone version is also in the works.

The company is offering APIs for other developers to incorporate EcoSpeed into their apps and services.

Other Clarian Labs projects include an electromagnetic hybrid battery that runs on carbon-neutral fuels to power equipment including robots, electric vehicles and home generators. The company, which also operates as Clarian Power, separately developed a solar power module for the home that won a Consumer Innovation Award in the GE Ecomagination Challenge.

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