CHICAGO, May 4 (Xinhua) -- Amid a global slowdown in auto sales, General Motors (GM), Ford, and Fiat Chrysler (FCA) have accelerated model changeover and restructured their joint ventures in China, the world's biggest auto market.

In their recently released first quarter results, all the "Big Three" from U.S. auto industry hub Detroit reported decreased worldwide deliveries. Their volumes in China slid as well at a time when China's auto sales in the first quarter of 2019 were down 11.3 percent year over year.

As the three leading U.S. automakers strive hard in their home market, they are wasting no time in rolling out new models in China, in a bid to revitalize their performance there.

GM and its joint ventures in China delivered nearly 814,000 vehicles in China in Q1, down 17.45 percent from the same period of 2018.

Under increasing pressure from fierce competition, GM has planned a major model changeover in China this year, with a pledge to continuously improve the fuel efficiency of its vehicles and broadly apply its global technologies on models built and sold locally.

In the first quarter, GM's Chevrolet brand launched new Monza and Onix sedans in China.

In April, 15 new or refreshed Chevrolet vehicles were shown at Auto Shanghai 2019, this year's leading automotive event in China.

During the auto show, GM unveiled the all-new Chevrolet Trailblazer compact SUV and Tracker small SUV, as part of its effort to further strengthen the brand's presence in China.

"Chevrolet is bringing to China world-class vehicles that leverage GM's global resources and target our customers' specific needs," said Scott Lawson, general director of Chevrolet for SAIC-GM, a joint venture between the U.S. automaker and its Shanghai-based partner.

Cadillac, the luxury brand of GM, brought its six-seat SUV XT6 to the Shanghai auto show, the first time in Asia. It will also be the first localized global large luxury SUV in the market, said GM, and will be available later this year.

Buick, another GM brand, debuted its all-new Encore and Encore GX, two small/compact SUVs at the Shanghai auto show.

Buick also unveiled Velite 6, the brand's first all-electric vehicle, joining other global competitors in China's rapidly expanding new-energy vehicle market. Buick plans to introduce eight new and refreshed products this year and more than 20 new and refreshed models between 2019 and 2023 in China.

Another leading U.S. automaker Ford has also announced that it will launch more than 30 new vehicles tailored to Chinese consumers in the next three years, in order to make a quick turnaround in China.

During an April event in Shanghai, Ford said that among the new Ford and Lincoln vehicles to be introduced in China, at least 10 will be electric cars.

More importantly, as part of "Ford China 2.0" strategy, Ford will set up four centers in China, focused on innovation, design, products and new energy vehicles respectively.

"China is leading the world with smart vehicles, and is a key part of Ford's global vision for the future. We are excited about seeing more products developed in China, for China and from China," Ford President and CEO Jim Hackett was quoted as saying.

"Ford is deeply committed to China, and with our new China leadership team and vision, we're investing in the future -- a future that starts today," he added.

At the "Ford China 2.0" conference recently held in Shanghai, Ford launched SYNC+, a new in-vehicle infotainment system co-developed with China's IT giant Baidu for Chinese consumers.

Since July, Ford has taken urgent measures to address underperformance in China after it suffered a sharp decline in overall profits in the second quarter of 2018.

The sale of Ford-branded -- import and domestic -- vehicles totaled 74,651 in Q1 2019, down 48.4 percent year over year, a harsher reality Ford has to face in China than its Detroit peer GM.

The blue oval now tries to improve cost competitiveness with aggressive fitness actions, localize more products in China, as well as recruit more local talent to key management positions.

Fiat Chrysler, an Italian-American automaker, suffered a 47-percent-fall in its first quarter net profit amid decreased sales globally. Its combined shipments in Asia Pacific region were down 30 percent, primarily in China.

FCA said on Friday that several steps were taken to strengthen its business in Q1, and underlined the progress towards a restructure of its joint ventures in China.

FCA and GAC (Guangzhou Automobile Group) have recently announced changes to the organizational structure of their joint ventures in China. They have agreed to merge GAC Fiat Chrysler Automobiles Company and GAC Fiat Chrysler Automobiles Sales Company into one, effective on May 1, 2019.

The streamlined management "will accelerate the integration of industrial and commercial operations, more rapidly respond to changes in the Chinese market environment and enable delivery of even more competitive products and services to its customers," FCA said in a statement.

Mike Manley, CEO of FCA, said that with such a deeper integration of the business between FCA and GAC, and the next steps in improving competitiveness in China, they will be able to "better react to the demands of the Chinese market."