uel economy has become a bigger priority than ever for new-car buyers, but how does buying a fuel-efficient car, whether a hybrid or a high-mileage gasoline-powered car, stack up over the long run in terms of estimated operating cost?

To find out, we took several fuel-efficient gas cars that are at the top of the Environmental Protection Agency's rankings and pored over the data. All fuel-economy data from here on out is from the EPA.

Scion iQ 2012 Scion iQ


Scion iQ: The little iQ gets 37 mpg combined, making it the star of the subcompact class. The EPA estimates its annual fuel cost at $1,500 per year. Base price: $15,385. The iQ may be aimed at young buyers who live in the city, but $15K is a steep price of entry in this class.

Nissan Versa
2013 Nissan Versa


Nissan Versa: Nissan's smallest offering rules the compact class with 35 mpg combined city and highway and a $1,600 per year fuel cost. That outdoes its slightly bigger brother, the Nissan Sentra, by one mpg. Base price: $11,990. Nissan's Versa offers a lot of value in both sticker price and fuel economy, making it a solid choice for those who value low cost above all else.

2013 Nissan Altima
2013 Nissan Altima


Nissan Altima: At 31 mpg combined and a $1,800 per year operating cost, the Altima is tops among the mid-size class (excluding hybrids). Base price: $21,500. Considering that the popular Honda Accord takes second, at 30 mpg combined, the Altima has a leg up. We find the Altima to be a solid entry in the mid-size class, even if it's not as flashy as the Ford Fusion or the Hyundai Sonata.

2013 Ford Taurus SHO
2013 Ford Taurus SHO

Large Cars

Ford Taurus: The best "mainstream" large car at 26 mpg combined, the Taurus will cost you about $2,100 in fuel per year. Base price: $26,600. Sure, the Taurus seems boring, but it's roomy, offers plenty of modern tech features, and has a relatively low base price for its class.

2013 Audi A6 2013 Audi A6

Luxury/Upscale Sedan

Audi A6: Audi's svelte mid-size A6 gets top billing in the luxury/upscale sedan class, at 28 mpg and $2,150 in fuel costs per year. Not too shabby for a car of its caliber. Base price: $42,200. It's hard to argue with a luxury sedan that offers good looks and high fuel-efficiency.

2013 Toyota Prius C 2013 Toyota Prius C


Toyota Prius C: Toyota's small urban runabout gets 50 mpg (making it the cream of the hybrid crop) and will cost $1,100 per year in fuel to operate. Base price: $18,950. The Prius C is cheap, but for hybrid buyers on a budget, it won't cause the bank account to bleed dry.