The first generation Sonata, which was introduced in 1985, was a facelifted version of the Hyundai Stellar with an engine upgrade, and was withdrawn from the market in two years due to poor customer reaction.

In 1987 Hyundai added two tone color schemes and a trip computer option, but sales soon went down and the car was discontinued in December of that year.

[6] It was sold in New Zealand (right hand drive)[citation needed] with the 1.6-liter Mitsubishi engine with the five-speed manual gearbox; an automatic transmission was an optional extra.

At one time, in the South Korea, there was a rumor that if students had the S-shaped emblem, they could go to a prestigious university (Seoul National University), and if they had the letter III, they could get a score of 300 on the College Scholastic Ability Test, which led to the Onata incident in which test takers secretly removed the Sonata III emblem.

The first generation Kia Optima (marketed as the Magentis outside the United States) was also based on the EF Sonata, sharing doors and roof panels.

This model is only available in the Chinese market and comes with a 1.8 or 2.0 liter engine with transmission choices consisting of a five-speed manual or a four-speed automatic.

The 2.0-liter gasoline version was only sold in Korea and proved more popular there due to added gas, tax and insurance savings.

Diesel versions are available in Europe, New Zealand and Singapore, where they are a popular replacement for the Toyota Comfort taxi cab.

[25] The redesign features revised engines, front fascia and chrome 3 bar grille, taillights (turn signals became red in North America only), jewel-projector headlights, new 10-spoke alloy wheel design for the Limited models (as opposed to sharing the 5-spoke design from the SE model), and an extensively revised IP (Instrument Panel).

[26] Hyundai adopted "slush molding", a production technique that enables a much higher grade of texturing and shaping of the IP surface.

[27] Redesigned gauges feature a blue backlight, and a touch-screen navigation system, optional on the Limited trim level only, includes satellite radio capability.

[28] Bluetooth capability is available as an optional unit, separate from the audio or navigation system, and all models include both a USB port along with an auxiliary input jack.

An optional USB adaptor cord allows integration of an iPod, and chrome interior door handles are standard on the Limited trim.

GLS, SE and Limited models feature a newly available, manually shiftable five-speed automatic transmission marketed as "Shiftronic".

[35] The US version of the sixth generation Sonata was unveiled at the 2009 Los Angeles Auto Show, with sales beginning in 2010 for the 2011 model year.

The i45 has also been discontinued in Colombia, and replaced with the smaller i40 sedan, leaving Singapore and New Zealand as the only two markets still selling the vehicle under the i45 name at that time.

[62] It also retains the 2.4-liter, multi-port fuel injected, four-cylinder engine, which uses a modified Atkinson cycle achieved via VVT and a compression ratio of 13:1.

[62] Standard features include Bluetooth, Satellite radio, dual-zone climate control, auxiliary and USB jacks, a CD Player, six-speaker surround system, 16-inch alloy wheels, automatic headlights, LED running lights, fog lights, heated mirrors, keyless ignition/entry, push-button start, cruise control, an eight-way power driver seat, tilt-and-telescoping steering wheel, heated front seats, and Hyundai's BlueLink emergency communications system.

The Theta-II engine produces 274 horsepower (204 kW) and 269 lb⋅ft (365 N⋅m) of torque while achieving an efficiency rating of 34 mpg‑US (6.9 L/100 km; 41 mpg‑imp) highway, beating the specs provided by the 3.3-liter Lambda V6 offered in the previous model.

While the previous model incorporated significant aesthetic changes and sold successfully within the U.S., sales in Korea failed to meet expectations.

[69] In the United States, the 2015 Sonata was available in base SE, economy-minded Eco, midlevel Sport, and range-topping Limited trim levels.

The Eco trim was powered by a 1.6L turbocharged inline-4 (I4) gasoline engine paired with a seven-speed dual clutch (DCT) automatic transmission.

The dashboard was reshaped, with new air vents on the driver's side and a larger touch screen that is compatible with Apple CarPlay and Android Auto.

The Hyundai Blue Link telematics system was also upgraded to be compatible with Amazon Echo and Google Home devices.

[70] A mid-trim SEL trim level was also added for 2018, with standard features such as Hyundai Blue Link in-vehicle telematics system, SiriusXM Satellite Radio, A/M-F/M HD Radio, and a power-adjustable front driver's bucket seat also became available for 2018, and both the base SE and Eco trims lost those features as standard equipment.

As part of the seventh-generation Sonata, Hyundai announced the release of a plug-in hybrid variant scheduled for market launch in the second half of 2015.

Despite being sold in the North American market as mid-sized, the cabin volume places it in the U.S. Environmental Protection Agency's full-size classification.

[78] The eighth-generation Sonata uses a new third-generation architecture and uses Hyundai's latest "Sensuous Sportiness" design language which was first previewed by the Le Fil Rouge concept.

The N Line is powered by a turbocharged 2.5-liter Smartstream four-cylinder gasoline engine producing 290 hp (294 PS; 216 kW) and 311 lb⋅ft (422 N⋅m; 43.0 kg⋅m) of torque, mated to an eight-speed wet dual-clutch transmission, sharing its powertrain combination with the 2021 Kia K5 GT.

[80] In addition to the upgraded engine and transmission, the Sonata N Line also features more aggressive exterior and interior styling over non-N Line Sonatas (these include larger, special aluminum-alloy wheels and tires, darkened exterior trim, a special black-painted grille, dual exhaust pipes, "N Line" badging on the rear trunk lid and leather-wrapped steering wheel, red interior stitching, special interior trim, and combination leather and Alcantara-trimmed seating surfaces).