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"  La Jolla, California\u2014Recent research by Hyundai revealed that U.S. drivers spend 58 percent of their driving time, on average, on highways. As applied to a hybrid, that news is interesting, suggesting that highway fuel mileage is at least as important as the improved city mileage on which most hybrid projects are concentrated. Hyundai also tried to balance costs in the new Sonata Hybrid, offsetting the price of high-tech batteries with sensible drivetrain specifications. The end result is a car that achieves its best fuel mileage on the highway\u2014a best-in-class 40 mpg according to the company&amp;#039;s estimates\u2014with city consumption slightly down on that, at 36 mpg. This contrasts sharply with the competitive hybrids in the segment, all of which achieve their best fuel consumption in the city. The company also sought to provide more power, better acceleration and lower mass than the opposition, and succeeded in most of these areas, according to Hyundai&amp;#039;s findings. It was defeated in just one area, weight: The Nissan Altima Hybrid weighs 13 pounds less.  The Specs The importance of highway fuel consumption led Hyundai&amp;#039;s development work on its new Sonata Hybrid Blue Drive system in directions not followed by other hybrid manufacturers. For example, Hyundai chose to utilize a more or less conventional six-speed automatic transmission instead of the CVT commonly picked for the job. Hyundai also opted for the latest lithium-polymer battery cells rather than the nickel-metal-hydride cells used in most other vehicles of the type. Using 72 cells wired in series, the battery pack produces 270 volts and 5.3 amp-hours. These LIPB cells offer better energy density than NiMH equivalents, along with less weight, volume and internal resistance. They also boast a longer cycle life and greater efficiency, and allow improved state-of-charge estimation. The battery pack is mounted behind the rear seat, where all cells are independently monitored for temperature and automatically cooled when necessary. Using manganese spinel chemistry, Hyundai claims, the LIPM cells have electrodes that are less subject to expansion and contraction cycles during charging and discharging, and are resistant to the cracks that occur in the electrodes of older lithium-ion cells and shorten their life. The gas engine is a Theta II 2.4-liter inline four converted to the Atkinson cycle (a relatively shorter compression duration to exploit the expansion cycle), which produces 166 hp at 6000 rpm and 154 lb-ft of torque at 4500 rpm, according to Hyundai&amp;#039;s latest estimates. A clutch marries (and separates) the gas engine from a permanent-magnet synchronous electric motor capable of 40.8 hp and 151 lb-ft of torque. A six-speed automatic transmission, unusual in not being equipped with a lockup torque convertor, attaches to the back of the electric motor, and it offers Hyundai&amp;#039;s Shiftronic manual selection system as well as conventional auto shifting. A separate hybrid starter/alternator handles starting chores instead of the electric motor, which is also a departure from standard hybrid practice. Hyundai&amp;#039;s senior VP of hybrid-electric vehicle development, Ki-Sang Lee, makes much of the company&amp;#039;s attention to aerodynamics. The Sonata Hybrid, he points out, has a full underbody fairing and an active air flap system in the car&amp;#039;s nose that blocks off much of the radiator at high speed to improve the car&amp;#039;s drag performance. Its drag coefficient (Cd) is an impressive 0.25, according to Hyundai&amp;#039;s claims. The Drive Just like other hybrids we&amp;#039;ve driven, the Sonata does not start when switched on. It just comes to life, with its various control lamps and electroluminescent instrumentation lighting up like a city at dusk. It might not even start the gas engine after you select drive and press on the accelerator, and will often move off silently, eerily, under electric power. In fact, the Sonata Hybrid can function as a pure EV up to 62 mph if the state of charge of its battery pack will allow it. We all asked how far it would go at 62 mph on pure electric power, and the Hyundai personnel, somewhat bemused by trying to calculate the various factors, finally admitted that they now suggest just one mile. But it could be more. It all depends. Other than gliding around in EV mode from time to time, the Sonata feels pretty much like a conventional car. The action of its six-speed automatic reinforces the sense of normality inside the car, since it never suggests that weird disconnect between revs and speed with CVTs that engineers call &amp;quot;motorboating.&amp;quot; You can&amp;#039;t really discern the contribution made by the electric motor, but with over 200 hp on tap from the conjoined motors, the Sonata simply steps off and accelerates briskly. It can run 0-to-60s in just over nine seconds, which is, again according to company claims, ahead of the obvious rivals from Toyota, Ford and Nissan. Although the additional components obviously add weight (the batteries alone add 96 pounds), it&amp;#039;s not very noticeable in the Sonata. The ride is supple but fairly well controlled, and the electric steering assist is among the best in the business, with natural weighting and a nicely finessed off-center transition. It provides path control that is both poised and accurate. We drove the car at an event shared with the new Sonata 2.0T, and the Hybrid was allocated a shorter route. Hyundai&amp;#039;s management also encouraged all drivers to compete in an economy run to see who could get the best mileage. The results were remarkable, even if the exercise did much to cloud the impression of the car&amp;#039;s everyday personality. Our car achieved well over 40 mpg, even with my brief\u2014and fairly profligate\u2014attempts to gain an inkling of the car in a normal driving environment. Someone was reported to have squeezed 57.7 mpg from the car on the same route. Despite the exterior styling and detail differences between the Hybrid and the rest of the Sonata line, it&amp;#039;s the similarities we like best. The thing drives just like another good car, and although some effort has been made to provide it with distinctive exterior and interior features, along with the obligatory hybrid-function displays, the Sonata Hybrid easily assumes a no-big-deal operational demeanor. With high-spec Sachs shocks and generous brake and tire sizing, the Sonata actually managed to evince a touch of sporty-hybrid panache. At least, when we weren&amp;#039;t creeping along sparing fuel, it did. But we&amp;#039;ll have to confirm that when the gas misers are not around to queer our pitch. The Bottom Line With hybrid demand flagging somewhat in an atmosphere of relatively stable gas prices, one might wonder why Hyundai would bother to introduce this car. Well, the company wants to improve upon its industry-leading corporate fuel-economy status. It broadens the showroom offerings and promises to lure hybrid-friendly shoppers who don&amp;#039;t need the car to yell &amp;quot;green&amp;quot; from the rooftops. Finally, starting somewhere in the mid-20s, Hyundai promises to do what it does best, which is undercut the opposition. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/cars/hybrid-electric/reviews/a6218/2011-hyundai-sonata-hybrid-us-test-drive/>