Which fuel-efficient car is most fuel efficient? In the latest “Fuel-Sipper Smackdown” from automotive information site Edmunds.com, the top fuel sipper of the year is the 2011 Chevrolet Volt.

The Fuel-Sipper Smackdown 4, which pitted efficient vehicles of all sizes and technologies against each other in three real-world driving environments — country highway, interstate highway and city route — found the Volt coming in number one at 41 miles per gallon and 99.5 miles of electric range. The Volt also ranked tops in money spent: $88.55 for gas and electric expenses combined.

The next best performer in mileage, the 2011 Volkswagen Jetta TDI, registered 37.2 mpg, followed by the 2012 Fiat 500 (36.9 mpg), the 2011 Kia Optima Hybrid (33.6 mpg) and the 2011 Hyundai Elantra (33.2 mpg). Second place in cost effectiveness went to the 2012 Fiat 500 ($88.77), followed by the 2011 Kia Optima Hybrid ($89.15), the 2011 Hyundai Elantra ($90.03) and the 2011 Volkswagen Jetta TDI ($90.88).

“As long as the driver can recharge the battery, the Volt’s performance both on our interstate highway route and our city route placed it above and beyond the four other fuel-sippers,” said James Riswick, automotive editor at Edmunds.com. “But figuring out the Volt’s thriftiness requires a mathematician and a whole lot of perspective.”

Edmunds.com’s editors said that the biggest surprise of the pack was the 2012 Fiat 500. The Fiat was the only vehicle Edmunds tested that either met or exceeded its EPA mpg estimates on every leg of the test. With its tiny engine and manual transmission, the cost to run the small car was just 22 cents more expensive than the Volt.

However, they added, while hybrid and electric cars might save their owners money at the gas pump, it might not be enough to offset the car’s purchase price.

• How to give a truck a dainty fuel appetite? Tire smarts
• GE, Coca-Cola among latest firms to joint Clean Fleet effort
• Five steps to a greener fleet