Gas, electric, hybrid -- which is best for you?

When Douglas Tiffany's grandfather emigrated from England around 1910, he used his woodworking skills to make models of cars that would be built in Detroit.

A century later, Tiffany is working with cars, too -- but in a distinctly updated medium.

Tiffany, an assistant extension professor at the University of Minnesota Twin Cities campuses, has developed an online spreadsheet tool that allows car buyers to figure out what kind of vehicle would be best for them -- conventional, hybrid or electric.

The spreadsheet -- which can be downloaded at Bit.ly/u970at -- allows buyers to compare conventional vehicles to hybrids such as the Toyota Prius, electric vehicles such as the Nissan Leaf, and extended-range electric vehicles such as the Chevrolet Volt. A short video on the site shows you how to use the spreadsheet. If you want to know even more, you can watch an hour-long video of a lecture Tiffany delivered on the subject.

The spreadsheet makes certain assumptions, such as the price of a particular type of vehicle, the interest rate charged on a car loan, and the expected miles per gallon of gas or kilowatt hour, and calculates the costs and carbon footprint over 15 years.

Car shoppers can insert figures such as the number of miles they drive per year to determine if a conventional, hybrid or electric car is the best value for them or will reduce their carbon footprint.

An agricultural energy researcher, Tiffany started the car-comparison project a couple of years ago when his brother mentioned he was considering buying a hybrid. "I said, 'Well, I think I can work out a good way to make this comparison,' " Tiffany said.

"I could imagine a household where one member says, 'We really have to do something different. We really have to reduce our carbon footprint,' and another member says, 'Can we afford it?' " Tiffany said. "I was able to bring those two things together and quantify them."

The web site has generated 4,300 visits since November. Shortly after it went up, an Chevrolet dealership in Indiana commented on how well it identified aspects of the Volt, according to Tiffany.

Tiffany's brother eventually bought a conventional car because it made the most sense for his type of driving. Some audience members at Tiffany's lectures who had been enthusiastic about buying a hybrid or electric car were disappointed to learn it didn't make economic sense.

Tiffany, who drives a 1998 Subaru Legacy, is keeping his options open.

"I calculate what sort of a carbon tax you are charging yourself by driving one of these vehicles," Tiffany said. "As an overall statement, I'd say we're really moving into an exciting time. The hybrids have come of age. They're known as reliable vehicles that do what they're supposed to and really have very few problems. They've kind of moved into the mainstream, and there will be many more types of hybrids and there will be many more electric vehicles coming out, too."