Best part of China is mountain.Yes. But China's population density is only about 54% of UK's. See
For UK, the vehicle ownership is 510 per 1000 persons. So China can have a higher vehicle ownership than 510 per 1000 persons.
320 vehicles/1000 persons is only about 63% of UK's per capita ownership.
To reach UK's level, China has to produce about 500 million more vehicles. At a current production rate of 24 million a year and a 10% growth rate, it will take 10 years at least.
Exactly what's unbalanced?
The coastal regions has very high population density.
Guangdong has 600 person per sqkm population density.
England has more than 300 person per sqkm, ad UK 271.
US New York State has a pop density of 162, and the US 33 person / sqkm.
So, I don't think that the car ownership rate can go above the UK level ( and I think it will be way lower than that in long term) .