A retired couple from Qingdao, Shandong province, on the roof of their motor home during a tour of Hainan province.[Photo by Liu Hailong/China Daily]

More than 60 percent of domestic holidays being taken in China are now "self-drive", according to new research, prompting calls for an expansion of the country's highway network and better roadside hospitality facilities.

The study, which surveyed tourists at hotels and tourist attractions in 40 cities in Jiangsu, Zhejiang and Anhui provinces and in Shanghai, said that self-drive holidays contributed more than 100 billion yuan ($15.68 billion) to those region's tourism income, and 1 trillion yuan nationally.

"Some 300 million licensed drivers, and increasing numbers of private cars, have made self-drive touring part of their lifestyles, said Wang Zheng, the deputy head and a researcher at Shanghai Academy of Social Sciences, which compiled the figures.

More than 2.2 billion self-drive trips were made in 2014, said Wang.

The research, jointly carried out by Xinhua News Agency's Shanghai bureau, the Shanghai Academy of Social Sciences, and the Yangtze River Delta Self-Driving Tour Experts Committee, said that the cities of Hangzhou, Suzhou, Shanghai, Ningbo and Wuxi were the region's most popular destinations, due to their rich tourism-friendly facilities, cultural heritage, quality services and popular local cuisine.

Self-drive tourists are spending more than the average tourist per head: some 5,000 yuan per year, according to the research.

Five percent of the 120,000 tourists questioned said they spend in excess of 10,000 yuan on self-drive tours over the past 12 months.

The increasing number of self-drive holidaymakers, meanwhile, has also pushed up demands on catering and the quality of service at expressway services areas.

Two-day trips were the most popular (a resounding 90 percent), with many saying they enjoyed staying overnight at their destinations, according to data from tuniu.com, the online booking platform.

"There are many incentives for choosing self-drive tours," said Zhang Zhiqiang, a 28-year-old Shanghai school teacher.

"Sometimes I simply drive two hours from Shanghai to stay in Suzhou, to eat some local seasonal food, such as meat-stuffed moon cakes in autumn or crabs in early winter.

"If there are any events going on such as art exhibitions, I may stay overnight for a day-tour－I'm pretty flexible," said Zhang, who said he spends an average 1,500 yuan on eating, admission tickets to museums and shows, hotels, road tolls and gas during a typical trip.

The rising demand for self-drive tours has also helped boost sales of Sport Utility Vehicles, said market insiders.

"It is obvious that SUVs are growing in popularity among Chinese car buyers," said Chang Xiawei, the sales manager with a United States-based auto brand in Shanghai.