Question: Which South Korean mid-size car is one of the Nissan Altima's largest competitors?
Context: The Infiniti QX70 (formerly called the Infiniti FX until 2013) is a mid-size luxury crossover SUV produced by the Nissan-owned Infiniti luxury vehicle brand between the 2003-2017 model year.  The FX replaced the QX4 as Infiniti's mid-size SUV, although the QX4 was larger than the FX.  It shares the same FM platform as the rear-wheel drive Nissan 370Z, and it "made no claims of climbing mountains."  Rather, its aggressive shape promised style and quick handling.  The similarly sized Nissan Murano is based on the same D platform as the front-wheel drive Nissan Altima.  The FX and QX56, that do not have Nissan-branded equivalents, are not sold in Japan. The Nissan Teana is a mid-size car produced by Nissan of Japan.  It is exported as the Nissan Maxima and Nissan Cefiro and Nissan Sentra to certain markets.  It replaces the Nissan Bluebird and Cefiro.  It shares a platform with the Nissan Maxima and Nissan Altima which are sold in North America, as well as the Japanese market Presage minivan.  The Teana has been available in East Asia, Russia, Ukraine, South Asia, ASEAN, Australia, New Zealand, Latin America and the Caribbean. The 2013 Clipsal 500 Adelaide was a motor race for V8 Supercars held on 2 and 3 March 2013.  The event was held at the Adelaide Street Circuit in Adelaide, South Australia, and consisted of two races of two hundred and fifty kilometres in length.  It was the first round of the 2013 International V8 Supercars Championship, and marked the racing debuts of the Holden VF Commodore, Mercedes-Benz E63 AMG, and Nissan Altima L33, all of which were entered in the series under the brand-new "Car of the Future" regulations; Ford continued to use the FG Falcon model raced in previous years, but built to Car of the Future specifications. ]A 2001 Nissan Altima, 1N4DL01D81C212547 is the VIN of a blue rental car belonging to Alamo Rent a Car, that was found in the Portland International Jetport parking lot, following the September 11, 2001 attacks.  It was issued a Massachusetts license plate 3335 VI. Hybrid Synergy Drive (HSD) is the brand name of Toyota for hybrid car drive train technology.  It is used in its Yaris, Auris, Prius, Avalon Hybrid, RAV 4, Highlander Hybrid, Camry Hybrid, Estima, Alphard, Lexus RX 400h/RX 450h, Lexus ES 300h, Lexus GS 450h, Lexus LS 600h/LS 600hL, Lexus CT 200h, Lexus IS 300h, Lexus HS 250h and Lexus NX 300h automobiles. Toyota also licenses its HSD technology to Nissan for use in its Nissan Altima Hybrid.  Its parts supplier Aisin Seiki Co. offers similar hybrid transmissions to other car companies. The Nissan Altima (Japanese: 日産・アルティマ ) is a mid-size car which has been manufactured by Nissan since 1992.  It is a continuation of the Nissan Bluebird line, which began in 1957.  The Nissan Altima mainly competes against cars such as Chevrolet's Malibu, Ford's Fusion, Honda's Accord, Hyundai's Sonata, Mazda's Mazda6, Subaru's Legacy, Kia's Optima, Toyota's Camry and Volkswagen's Passat. The Subaru Legacy is a mid-size car built by Japanese automobile manufacturer Subaru since 1989.  Part of the original design goals for the Legacy model was to provide Subaru a vehicle in which they could compete in the lucrative North American midsize market against competitors Honda Accord, Toyota Camry, Mazda6, and Nissan Altima.  Higher performance variants of the Legacy are offered as competitive alternatives to compact executive cars such as the Audi A4, Alfa Romeo 159 and BMW 3 Series.  The Legacy also serves as Subaru's flagship car. The Infiniti J30, or Nissan Leopard J Ferie ("férié" is French for "holiday") in Japan, was a rear wheel drive luxury car.  The J30 went into production on April 7, 1992 as a 1993 model to replace the M30 (which was a coupe), and was launched in the United States after its competitor, the Lexus GS.  The car was designed to slot between the smaller G20 and the larger Q45, as Infiniti's first mid-size sedan to compete directly with the Acura Legend.  Also, it was fairly small but featured rounded styling uncharacteristic of the crowded executive car class, that is now reminiscent of a four-door coupé.  Chief designer for the J30 was Jerry Hirshberg, president of Nissan Design International (NDI) and exterior designer Doug Wilson in 1988-1989.  Design work was frozen in 1989.  In a promotional video produced in 1994, it was referred to as a "personal luxury sedan" as attempt to define it as a four-door coupé.  It has the round looks of the Nissan Altima/Bluebird U13. The Hyundai Sonata (Korean: 현대 쏘나타 ) is a mid-size car produced by the South Korean manufacturer Hyundai since 1985.  The first generation Sonata was introduced in 1985, which was a facelifted Stellar with an engine upgrade, and was withdrawn from the market in two years due to poor customer reactions.  While the original was only sold in South Korea, with limited exports to Canada and New Zealand, the second generation of 1988 was widely exported. The Ford Fusion is a four-door, five passenger mid-size sedan manufactured and marketed by Ford across three generations in gasoline and gas/electric hybrid variants.  Introduced for model year 2006, the Fusion is manufactured at Ford's Hermosillo Stamping & Assembly plant along with its rebadged variant the Lincoln MKZ — and formerly with its now discontinued rebadged variant, the Mercury Milan, all sharing the CD3 platform.  The Ford Fusion mainly competes against cars such as the Buick Regal, Chevrolet Malibu, Honda Accord, Hyundai Sonata, Kia Optima, Mitsubishi Lancer, Nissan Altima, Toyota Camry and Volkswagen Passat.
Answer: Hyundai Sonata