The latest fleet vehicle at the Association of Illinois Electric Cooperatives in Springfield gets 100-plus miles per gallon, as long as the trip is only 40 miles or so.

As part of a national research project, the association recently converted a Toyota Prius by installing a backup lithium battery pack. The Illinois association is one seven nationwide participating in the experiment through the Cooperative Research Network of the National Rural Electric Cooperative Association.

The U.S. Department of Energy is also supporting the research.

“We’ve tested it enough to know what it’s capable of. The real issue is, once you get up to highway speeds, it’ll revert back to regular Prius mileage standards of 40 to 45 miles per gallon,” said association spokesman John Lowery.

Lowery, who has taken a few spins in the Prius since it was converted two weeks ago, said performance data is automatically uploaded to the national organization from a data module in the vehicle.

“We’re encouraging all of our employees to drive it and get a feel for what’s it’s like,” he said.

Lowery said the lithium ion batteries are essentially the same type used in laptop computers, though the price tag is quite a bit steeper.

“The batteries were $10,000. It’s expensive, but we’re hoping the price will come down as the technology improves,” he said.

Tim Landis can be reached at (217) 788-1536 or tim.landis@sj-r.com.