Question: When did the maker of the Acura Legend, the largest auto company in the world, and Nissan open US assembly plants?

Knowledge 1: Acura Legend
The Acura Legend is a mid-size luxury/executive car manufactured by Honda. It was sold in the U.S., Canada, and parts of China under Honda's luxury brand, Acura, from 1985 to 1995, as both a sedan, which was classified as a full-size car, and a coupe, which was classified as a mid-size car (similar to how the Honda Accord is set up today). It was the first flagship sedan sold under the Acura nameplate, until being renamed in 1996 as the Acura 3.5RL. The 3.5RL was the North American version of the KA9 series Honda Legend. [SEP] Knowledge 2: Automotive industry
Rank Group Country Vehicles Toyota Japan 10,213,486 Volkswagen Group Germany 10,126,281 Hyundai South Korea 7,889,538 General Motors United States 7,793,066 5 Ford United States 6,429,485 6 Nissan Japan 5,556,241 7 Honda Japan 4,999,266 8 Fiat Chrysler Automobiles Italy / United States 4,681,457 9 Renault France 3,373,278 10 PSA France 3,152,787 11 Suzuki Japan 2,945,295 12 SAIC China 2,566,793 13 Daimler Germany 2,526,450 14 BMW Germany 2,359,756 15 Changan China 1,715,871 [SEP] Knowledge 3: 1973 oil crisis
Some buyers lamented the small size of the first Japanese compacts, and both Toyota and Nissan (then known as Datsun) introduced larger cars such as the Toyota Corona Mark II, the Toyota Cressida, the Mazda 616 and Datsun 810, which added passenger space and amenities such as air conditioning, power steering, AM-FM radios, and even power windows and central locking without increasing the price of the vehicle. A decade after the 1973 oil crisis, Honda, Toyota and Nissan, affected by the 1981 voluntary export restraints, opened US assembly plants and established their luxury divisions (Acura, Lexus and Infiniti, respectively) to distinguish themselves from their mass-market brands.
Knowledge 1: Acura Legend
The Acura Legend is a mid-size luxury/executive car manufactured by Honda. It was sold in the U.S., Canada, and parts of China under Honda's luxury brand, Acura, from 1985 to 1995, as both a sedan, which was classified as a full-size car, and a coupe, which was classified as a mid-size car (similar to how the Honda Accord is set up today). It was the first flagship sedan sold under the Acura nameplate, until being renamed in 1996 as the Acura 3.5RL. The 3.5RL was the North American version of the KA9 series Honda Legend. [SEP] Knowledge 2: Automotive industry
Rank Group Country Vehicles Toyota Japan 10,213,486 Volkswagen Group Germany 10,126,281 Hyundai South Korea 7,889,538 General Motors United States 7,793,066 5 Ford United States 6,429,485 6 Nissan Japan 5,556,241 7 Honda Japan 4,999,266 8 Fiat Chrysler Automobiles Italy / United States 4,681,457 9 Renault France 3,373,278 10 PSA France 3,152,787 11 Suzuki Japan 2,945,295 12 SAIC China 2,566,793 13 Daimler Germany 2,526,450 14 BMW Germany 2,359,756 15 Changan China 1,715,871 [SEP] Knowledge 3: Ford Motor Company Assembly Plant
The Ford Richmond Plant, formally the Ford Motor Company Assembly Plant, in Richmond, California, was the largest assembly plant to be built on the West Coast and its conversion to wartime production during World War II aided the United States' war effort. The plant is part of the Rosie the Riveter/World War II Home Front National Historical Park and is listed on the National Register of Historic Places. It currently houses the National Park Service visitor center, several private businesses and the Craneway Pavilion, an event venue.
Knowledge 1: Acura RLX
The Acura RLX is a full-size luxury sedan manufactured by Honda and sold under their Acura division, released in 2013. Succeeding the Acura RL, the RLX offers two versions, a front-wheel drive base model equipped with Acura's Precision All-Wheel Steer (P-AWS) four-wheel steering system, and a hybrid variant featuring SH-AWD that serves as Acura's flagship. The JDM version, the Honda Legend, is only offered with the SH-AWD powertrain. [SEP] Knowledge 2: Automotive industry
Rank Group Country Vehicles Toyota Japan 10,213,486 Volkswagen Group Germany 10,126,281 Hyundai South Korea 7,889,538 General Motors United States 7,793,066 5 Ford United States 6,429,485 6 Nissan Japan 5,556,241 7 Honda Japan 4,999,266 8 Fiat Chrysler Automobiles Italy / United States 4,681,457 9 Renault France 3,373,278 10 PSA France 3,152,787 11 Suzuki Japan 2,945,295 12 SAIC China 2,566,793 13 Daimler Germany 2,526,450 14 BMW Germany 2,359,756 15 Changan China 1,715,871 [SEP] Knowledge 3: 1973 oil crisis
Some buyers lamented the small size of the first Japanese compacts, and both Toyota and Nissan (then known as Datsun) introduced larger cars such as the Toyota Corona Mark II, the Toyota Cressida, the Mazda 616 and Datsun 810, which added passenger space and amenities such as air conditioning, power steering, AM-FM radios, and even power windows and central locking without increasing the price of the vehicle. A decade after the 1973 oil crisis, Honda, Toyota and Nissan, affected by the 1981 voluntary export restraints, opened US assembly plants and established their luxury divisions (Acura, Lexus and Infiniti, respectively) to distinguish themselves from their mass-market brands.

Answer: 1981