Gather round kids, it's time for "why do things in China cost so damn much?"
The Sparknotes version is this. The Chinese government slaps stiff import taxes on foreign-made cars,
and equally stiff taxes on luxury goods. The post-Cultural Revolution phenomenon of conspicuousness to the point of tackiness means that no Chinese would want to be seen with an older Quattroporte, a car that costs less than $45k in Canada. They want the 2013 Quattroporte GT-S with all the options, to be seen in. That's why it costs £275k. (A new S500 costs 2.1 million RMB (just over $350k) which is triple the cost of the equivalent in Canada (the S550).
By the way it's the same in all of Asia, steep taxes to protect local industries or encourage public transport. The most extreme example: In Singapore a Honda Accord costs S$150k. But Singapore's subway is amazing, it blows Skytrain out of the goddamn water.
On a side note: Because China is still a poor country (the average factory worker in Beijing or Shanghai makes less than $300 a month), someone with a new model luxury vehicle is really, really, really, REALLY fucking rich. And they will pay in cash for these cars, with bags full of yuan in some cases. These mega-ballers are more often than not connected to the Communist Party, either they own businesses that are in favour with the CCP or they are corrupt politicians themselves. They will send their kids abroad to study, I have heard anecdotes of high school kids getting their own house in Shaughnessey or Dunbar, all paid in cash by their parents. Many are good people I'm sure, but some are spoiled rotten ("My father is Li Gang", the Highway 99 street racers, the 599 GTO crash in Singapore).
Just to show you how fast China's economy is growing, 400,000 Audis were sold in China and HK in 2012, compared to 140,000 in the US.