The era of hybrids has arrived, and more than two dozen models in the U.S. auto market use a combination of a battery pack and a gasoline engine for propulsion. As the hybrid market matures, technological advancements — including further mileage gains — have become only incremental, and some new offerings are disappointing "me-toos." This makes careful shopping important.Traditionally, hybrid cars have been classified by powertrain: mild, single-mode and two-mode. Mild hybrids deliver the smallest boosts in mileage, usually up to 20 percent. Single-mode hybrids are best for lower-speed driving, where they can increase mileage by up to 40 percent. Two-mode hybrids are known for fuel economy gains at all speeds, plus providing enough juice for the needs of larger vehicles.

But you wouldn't purchase a hybrid vehicle for its label alone. You're interested in how it performs and serves you. With that in mind, here's a more practical way to think of hybrid cars, with highlights of some of the leading entries in each segment.

Real Fuel Sippers 2009 Ford Escape Hybrid, $29,645 This SUV is what passes for an oldie but goodie in the hybrid business. Ford introduced the first hybrid SUV in 2005, and the latest version of the hybrid Escape is still the mileage champ in the segment, at 34 mpg in the city and 31 mpg on the highway. The Escape boasts a slightly larger engine than in the previous model and relies on 20 more horsepower. Braking also offers an improved transition between electric- and gasoline-powered modes.

2010 Ford Fusion Hybrid, $27,270 (Base MSRP)Ford is taking it to the imports again with its newest hybrid, a smooth-driving, nicely equipped entry (along with its Mercury Milan cousin) that comes in at the top of the mileage charts in its segment. At 41/36 mpg (city/highway) compared with 23/34 for the entry-level gasoline-only model, the hybrid Fusion also handily bests its main midsize competitor, the Toyota Camry Hybrid. The Fusion Hybrid features the nifty SmartGauge with EcoGuide, an onboard computer that coaches drivers in how to command the vehicle in the most fuel-efficient way.

2010 Honda Insight, $19,800 Back in the mid-'90s, only true envirofreaks drove the Insight, the original two-seater hybrid in the U.S. market. But now, Honda is bidding for leadership in the category once again with a completely new Insight, this time a four-door hatchback version that will post 40 mpg in city driving and 43 mpg on the highway. It highly resembles a Prius, but with prices beginning under $20,000, Honda said it will be the lowest-priced hybrid on the market.

2010 Toyota Prius, $23,500 (est.)The car that defined the category is back in bigger and better form in its third generation. The hybrid sales champion — which emerged over the last couple of years as a metaphor for the entire segment — is growing slightly in size and somewhat significantly in mileage, with a new combined performance of 50 mpg, versus 46 mpg for the current model. The gas engine is slightly bigger and more powerful; the Prius' exterior is more aerodynamic; and there are now a host of options including a solar roof that powers the ventilation system.