SANTA MONICA, Calif. — Edmunds.com has released the results of its small car fuel economy challenge. Edmunds editors pitted the 2008 Toyota Prius against the 2008 Ford Focus, 2008 Smart Fortwo and 2005 Volkswagen Jetta TDI to determine which vehicle returned the best fuel mileage in each of the following five rounds:

Best back roads cruiser — 50 to 65 mph for 334 miles of back roads.

Best city roller — stop and go for 133 miles of Las Vegas city streets.

Best highway flier — a steady 75 mph for 209 miles of interstate.

Lowest fuel costs — which of the challengers saved us the most cash.

Greenest small car — which spewed the least greenhouse gases on our trip.

The highlights of the results are as follows:

-- The Toyota Prius, the overall winner, dominated the city driving test by returning 52.4 miles per gallon. The Prius also emitted the least greenhouse gas of all the competitors and had the lowest overall fuel costs.

-- The Volkswagen Jetta TDI recorded the best fuel economy in the back-roads driving and highway cruising tests, averaging 47.3 and 48.9 miles per gallon, respectively.

-- The Smart Fortwo scored second place in both the best city roller and lowest fuel cost rounds.

-- The Ford Focus performed well on the highway, averaging 37.5 mpg and beating the EPA figures of 35 mpg.

"As gas prices continue to rise, consumers should think about their daily commutes when shopping for a new or used fuel-efficient vehicle," said Phil Reed, Edmunds.com's senior consumer advice editor. "Each vehicle has its own personality and depending on how you drive the vehicle, you'll get different results."