Consumer Reports has published its final test results on the Chevrolet Volt, online and in the October issue, completing a seven-month, three-season evaluation. Tests were conducted on other fuel-efficient cars, including the Fiat 500, Honda Civic Hybrid, Lexus CT 200h, and Volkswagen Jetta TDI.

Hybrids, diesels, and small cars. Oh, my.
As the government recently advanced an ambitious new fuel-economy standard of 54.5 mpg, automakers are working on the technology and designs that will make that possible. The cars CR tested in this test group reflect some of the ways that manufacturer’s are stretching out gas mileage.

During our time testing the Volt, we found that fuel economy varies depending on weather and driving conditions, ranging from the equivalent of 99 mpg on electric power alone to a less impressive 29 mpg overall when running only on gasoline. The Volt proved inexpensive to run on short trips, but when the gas engine kicks in and trips reach 70 miles, traditional hybrids catch up in running costs. While the innovative combination of a large battery, electric motor, and gasoline engine works well, the Volt suffers from some practical shortcomings.

The Fiat 500 is nimble and easy to park, making it well suited to duty as a city car. But a noisy cabin, flawed driving position, and jumpy ride are drawbacks. The Fiat 500 Sport ($18,600 MSRP as tested,) is powered by a 101-hp, 1.4-liter four-cylinder engine that provides adequate acceleration and 33 mpg overall. The five-speed manual transmission’s gearing wrings out every drop of power on tap. The tiny luggage area holds only one large suitcase, but you can fold the rear seatbacks to expand the cargo area.

The Honda Civic Hybrid gets impressive fuel economy at 40 mpg overall, but the car has gone downhill, with sloppy handling, a choppy ride, long stopping distances, and a cheap-feeling interior. It suffers from pronounced road noise, which masks the relatively subdued engine and wind noise. The Honda Civic Hybrid ($24,800 MSRP as tested) is powered by a 110-hp, 1.5-liter hybrid engine that accelerates adequately. The continuously variable transmission is very smooth and responsive. Cost cutting is apparent throughout the interior, with cheap, hard plastics. Unlike in other Civics, the back seat doesn’t fold, and the battery encroaches on cargo space.

A small-sized luxury car with fantastic fuel economy sounds like a great idea, but it’s a dream not fully realized with the Lexus CT 200h. Despite its impressive 40mpg overall and some luxury appointments, nothing else is special about this least-expensive Lexus. Handling is responsive and secure, but acceleration is leisurely and the ride is stiff. The Lexus CT 200h Premium, ($32,012 MSRP as tested) is powered by a 134-hp, 1.8-liter, four-cylinder gas engine that was quite sluggish and gets 40 mpg overall in CR’s own fuel economy tests. The continuously variable transmission shifts smoothly. The interior is nice but more typical of a Toyota than a Lexus. The cargo area can hold just one suitcase and a duffel bag, but the split rear seatbacks fold down to make more space.

The new Volkswagen Jetta has a roomier backseat and a softer ride than its predecessor, but that’s where the improvements end. It rides well and absorbs bumps with good isolation, but too much road and wind noise seep in. Further, the interior looks and feels cheap. Handling lacks the agility and precision of previous generations. The Volkswagen Jetta TDI ($25,100 MSRP as tested) is powered by a 140-hp, 2.0-liter four-cylinder engine that provides adequate acceleration and 34 mpg overall. The six-speed manual transmission shifts smoothly. The trunk is sizable, and cargo space expands by folding the 60/40 rear seatbacks.

None of the models tested in this group are Recommended. The CT 200h, Jetta TDI, and Volt are too new for Consumer Reports to have adequate reliability information. The Civic Hybrid and 500 scored too low in CR’s testing to be recommended. Consumer Reports only Recommends vehicles that have performed well in its tests, have at least average predicted reliability based on CR’s Annual Auto Survey of its more than seven million print and Web subscribers, and performed at least adequately if crash-tested or included in a government rollover test.

Road tests and Full Track Reports are available to online subscribers.