Viable Alternatives to Rising Gas Prices

While many Americans are joining car and van pools to ease the pain at the gas pump, some drivers are taking more extreme measures.

Peter Nortman and Gregg Hanssen, two engineers in Monrovia, Calif., have found a way to enhance the Toyota Prius -- a gas-electric hybrid car that already gets as much as 50 miles to the gallon.

"We've taken out the original nickel-metal battery pack from Toyota and put in a larger lithium battery system," said Hanssen. "This battery system allows us to charge it at night and use the extra electricity during the day to get over 100 miles per gallon for the first 50 to 60 miles of the day."

By installing plug-in batteries, they boosted the electric reserve, giving the car super-high mileage for the amount of driving most people do in a day. The system costs $12,000, but the price would be less with commercial production.

Given the current spike in gas prices, some drivers are looking to fill their cars with a substance similar to what is used to cook french fries.

Country singer Willie Nelson, on the road again for his summer concert tour, is taking the opportunity to promote biofuel. It's basically cooking oil, new or recycled, which is used to power diesel engines. Mass production could make biofuel significantly cheaper.

"This one can help our environment," Nelson said. "It can help our farmers, it can help our truckers, it can help you and I get cheaper fuel for our cars and trucks."

Propane-powered cars, which are another fuel-saving option, comprise about 5 percent of the Los Angeles taxi fleet. Propane fuel stations are harder to find, but it's a more affordable alternative.

"It's about 80 percent of what gas costs," said Daniel Helman, who drives a propane-powered vehicle.

New technology is almost always more expensive in the early stages. But Nortman and Hanssen believe rising gas prices and falling technology costs will encourage drivers to consider new kinds of cars.

ABC News' Brian Rooney filed this report for "World News Tonight."