Personal preference

Like many drivers of modified cars, Zhang has found that the ability to customize is a big selling point, she said.

For the interior, BMW's signature combination of white and blue was partially replaced with gray, black and red according to Zhang's personal preferences.

The whole modification cost about 70,000 yuan.

Customized rims are popular items.

Apart from the "unique humming of the engine and the driving force that comes at any given moment", Zhang particularly enjoys deftly navigating Beijing's tricky traffic.

"It's like a game, and it would never be so fun without my car."

Female drivers are known to pay more attention to the exterior of the vehicles rather than their functions, said Mike Ma, vice-president of the Geely Automobile Research Institute.

"Women prefer vehicles with brighter colors, glamorous lighting and outstanding sound effects," he said.

"However, too much lighting on the front of the car should be avoided because it hinders the view and poses threats to drivers' safety."

While men would choose a professional cross-country vehicle to go to places like Tibet and Europe, women tend to prefer light and sporty ones for camping in the outskirts of town, he said.

Designers are now starting to accommodate this new wave of female drivers.

Vehicles like crossover utility vehicles combine a car chassis and features of a sport utility vehicle to cater to drivers who need a car adapted to city and off-road driving.

What women lack in strength, they make up for with their flexibility and carefulness, said their male counterparts.

"When driving in a desert, a female driver can sometimes do better because they are more sensitive to the road condition," said Jin Bo'en, a male all-terrain vehicle driver.

"Being a light driver also means you get through easier when come across a pit or a slope."

Although women are still a minority in the sphere, it does not mean they are satisfied with sitting back and letting the men lead the way.

Gong Zhaohui, 26, has been traveling in a cross-country vehicle for five years. A co-organizer of an off-road club, she has led fleets to Yunnan, Sichuan and Tibet. Gong took up car racing last year, competing with both male and female drivers on the track.

"I want to be a more professional driver. And racing with these people helps me improve faster," Gong said.

At the moment, the modified car business remains a gray zone in China.

Gong Zhaohui, 26, has led fleets to Tibet. Female drivers are increasing in the market for modified cars.

Only modifications to the exterior are permitted and all others are illegal, said Lu from CAMRTA.

The restriction has created a black market that is rife with fake products instead of one that is healthy and well regulated, he said.

The association is initiating a quick-response code system that aims to identify all the car components to avoid fake products. "The momentum of the market is irresistible, and it is time to make clear what is right and what is not," Lu said.