Question: When did the maker of the Acura Legend, the company that built Daihatsu Boon, and Nissan open US assembly plants?

Knowledge 1: Daihatsu Boon
The is a subcompact car produced by Japanese automaker Daihatsu since 2004, and also sold as the . The Passo is sold at "Toyota Corolla Store" Japanese dealerships. [SEP] Knowledge 2: 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. [SEP] Knowledge 3: Infiniti J30
The Infiniti J30, or Nissan Leopard J Ferie 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.
Knowledge 1: 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. [SEP] Knowledge 2: 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 3: Daihatsu Charmant
The Daihatsu Charmant is a subcompact sedan built by Daihatsu of Japan, based on the Toyota Corolla. It was replaced by the Daihatsu Applause. The Charmant was originally a spin-off of the Toyota Corolla of the 1970s; model changes paralleled those of the Corolla. All Charmants were fitted with Toyota inline-four engines, ranging from 1.2 to 1.6 litres. The word "charmant" is French for charming.
Knowledge 1: Daihatsu Boon
The is a subcompact car produced by Japanese automaker Daihatsu since 2004, and also sold as the . The Passo is sold at "Toyota Corolla Store" Japanese dealerships. [SEP] Knowledge 2: 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. [SEP] Knowledge 3: 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.

Answer: 1981