LITTLETON, Colo. -- Imagine driving 700 miles on just one tank of gas. That's what Ray Flesher says he's been able to accomplish ever since he converted his 2005 Toyota Prius to a plug-in hybrid vehicle.

"I've had this car for five years and have driven it 60,000 miles. Originally, I was getting as much as 52 miles per gallon. Now, I'm getting 97 miles per gallon," said Flesher during his first trip to the gas station in over a month.

The extra miles per gallon will be critical in the months ahead. He'll be making frequent trips across the Denver metro area.

"I'm going to use this to save money on my campaign. I'm running for Arapahoe County Clerk and Recorder in November," said Flesher.

Pro Auto Care mechanics recently installed a Hymotion plug-in conversion module into Flesher's car. It is a rechargeable lithium battery that extends the electric range of the vehicle and is recharged through a standard household electric outlet.

"You can have a vehicle that is going to save you a ton of money. It's going to pollute a lot less and it's going to lessen the dependency on foreign fuel," said Al Oramas, the president of Pro Auto Care.

Earlier this summer, Pro Auto Care became the first company in Colorado to install the Hymotion conversion kit. They are now backed up with orders.

"Now the gas motor, which is still in the vehicle, will not need to come on as often," said Oramas while assisting during a recent installation of the new battery and accessories into another Prius.

The Hymotion battery works directly with the car's existing hybrid battery and computer system. It does not void Toyota's warranty.

"You're not altering the car. You're extending the range of the battery. Hymotion is so confident with its system that they will back up the Toyota warranty," said Oramas.

Simply put, the plug-in conversion allows the car's computer to recognize and use the new added battery power first. It allows the car average close to 100 miles per gallon.

Once the Hymotion electric charge is drained, usually after 30 to 50 miles, the Prius goes back to standard operation.

Drivers can recharge anytime.

"You're going to have to grab an extension cord, come to the back of the vehicle and plug it in," said Oramas.

7NEWS wanted to know how this might affect energy costs.

"Has your electric bill gone up in the past month since this conversion?" asked 7NEWS reporter Jennie Castor.

"No, not at all. It fluctuates," said Flesher. He said he spends about 50 cents each time he plugs in and recharges the Hymotion battery. Its a price much less than a gallon of gas.

Right now this conversion kit is only available for Prius cars. Engineers are testing similar technology for future use in other hybrid vehicles.

The Hymotion plug-in conversion kits cost nearly $10,000. But Colorado and federal tax credits can reduce that price by as much as $6,000.

For additional information, visit Pro Auto Car Prius Conversion.