GreenRoad Technologies said Thursday that it has landed a $15 million investment to aid its quest to place electronic backseat drivers in vehicles as a way to cut down on accidents and save fuel.

The Redwood Shores, Calif.-based startup makes software and systems that warn drivers when they're accelerating too fast, braking too hard, or otherwise driving like jerks. Following the system's green, yellow and red-light warning systems can help cut accidents in half and average fuel use by up to 11 percent, it says.

The $15 million investment was led by DAG Ventures and joined by existing investors Benchmark Capital, Virgin Green Fund, Amadeus Capital and Balderton Capital. The company has previously raised about $20 million (see Improving Fuel Economy One Middle Finger at a Time).

GreenRoad sells its systems to government and commercial clients for fleet vehicles in the United States and United Kingdom, including Ryder, T-Mobile, Metroline and several insurance companies.

Beyond keeping track of people who drive for a living, it also works with insurers on programs to offer incentives to young drivers who can keep their driving habits within safe boundaries.

GreenRoad also sells direct to consumers. The business is based on a subscription model, promising that the fuel and accident savings it provides will quickly make up the cost (see Hemp Homes, Fish Food, Holographic Solar and Other Ideas).

The Environmental Protection Agency says that aggressive driving can lower average gas mileage by up to a third on highways, indicating that keeping it cool behind the wheel can have a big payoff.

GreenRoad isn't the only company looking to help drivers improve their habits. Marshall, Mich.-based Progressive Dynamics makes the Digital Fuel Mizer, a dashboard-mounted device that tells drivers when they're accelerating or braking in a sub-optimal fashion.

And Hayward, Calif.-based Davis Instruments makes the CarChip, which has been used by insurance company Progressive in a program to offer rebates to customers based on their driving habits.