The four-door midsize sedan is in many ways the heart of the car market. It’s also the segment that has the greatest number of head-to-head competitors with hybrid drive, which four automakers now have as an option on their mainstream midsize offerings. The Hyundai Sonata Hybrid claims the top green spot in this segment, earning an eRating of 154 and nosing out the Nissan Altima Hybrid, which scores a 152.
Of course, this doesn’t count the Toyota Prius. We handicap the choices covered in this article by excluding that uniquely optimized hybrid original, which has grown into midsize capacity but hardly pretends to be a standard sedan. The Prius’ eRating of 205 remains out of reach for most vehicles and is almost double that of the average midsize car eRating of 106.
Just released, the Hyundai Sonata Hybrid features an industry-first automotive engineering combination of a full hybrid system with a turbocharged direct-injection four-cylinder gasoline engine. This propulsion package delivers total gas-plus-electric oomph amounting to 209 horsepower, a level of output rivaling many V6 powertrains. The result is exceptional fuel economy given the performance capability.
Besides the Sonata and Altima hybrids, the other two entries in this segment are the Ford Fusion and Toyota Camry hybrids, which garner eRatings of 147 and 135, respectively. The Hyundai and Nissan offerings end up nearly nose-to-nose, with a less than one percent difference on the AutoEcoRating scale, and the Ford Fusion Hybrid isn’t that far behind. Although the Camry Hybrid brings up the rear it still emits 20 percent less pollution per mile than the average midsize sedan.
Among the four, the Hyundai Hybrid is the first use a lightweight lithium polymer battery pack. Nissan pioneered lithium-based batteries in its limited-release Altra EV over a decade ago. But like most other automakers to date, the Nissan’s current hybrid sticks with the reliable but heavy nickel-metal chemistry. That’s the type of battery still used in the other hybrids in this segment as well as in the Prius.
Hyundai’s “Blue Drive” hybrid system mounts the main electric motor in line with a 6-speed automatic transmission. This setup eliminates the torque converter and represents a totally new twist on powertrain design. To address the challenges of instantly starting and stopping the gasoline engine and providing smooth launches, Blue Drive uses an integrated starter-generator that is belt coupled to the engine. This allows the engine to restart when disconnected from the transmission, while the electric motor can deliver uninterrupted torque to the wheels. The result is a low-cost solution to a complicated engineering problem. Other manufacturers making full hybrids have addressed these issues with a split system, as epitomized by Toyota’s Hybrid Synergy Drive and the similar configurations used by Nissan and Ford.
The Sonata Hybrid’s design yields a highway fuel economy of 40 mpg. That’s higher than its 35 mpg city rating and represents a city-highway efficiency balance more like that of regular vehicles. This is in contrast to split-system designs that excel in urban driving, such as the Ford Fusion Hybrid’s best-in-class 41 mpg city rating.
Tailpipe emissions also factor into the eRatings and the Sonata Hybrid’s “Bin 2” emissions level is another reason why it edges out the competition. Among the four cars, only the Nissan Altima Hybrid certifies to a “Partial Zero Emission Vehicle” (PZEV) rating; that’s its only configuration but one of limited availability, explaining why its eRating comes so close to the Sonata Hybrid’s. Cleaner versions of the Sonata, Fusion and Camry hybrids are available in California, where the Sonata Hybrid still comes out on top and the Ford Fusion hybrid moves up to second place.