The electric-bus startup Proterra has raised $30 million in new funding, including $6 million from GM Ventures. The company uses relatively small battery packs to keep down costs, intending them to be recharged frequently at rapid-charging stations that can replenish them in less than 10 minutes.

Fuel-saving technology is important to transit agencies, especially now that diesel prices are high and volatile—a gallon of diesel costs a dollar more that it did a year ago. Proterra CEO Jeff Granato says each bus will save the transit agency $600,000 in fuel costs over the 12-year life of the vehicle, plus another $70,000 to $95,000 in maintenance costs. Electricity to charge the buses costs about 18 cents per mile, compared with about $1 a mile for diesel fuel. Granato says these savings make the total cost of an electric bus comparable to that of a diesel bus over the life of the vehicle, even though the electric bus costs more up front. (The company won't say how much the buses cost, but they do, apparently, need nearly $700,000 in fuel and maintenance savings to break even with diesel buses.)