Actually, I can't speed a sport car in Hong Kong?

It depends on your point of view.

Compared with those normal private cars, the supercars like Porsche, Ferrari may be not so suitable and practical in HK.
The limitation includes lots of cars, slow trafiic, many speeding blocks, few straight and wide rd or highways etc.

If you are in Europe, as there are lots of wide and straight roads and highways with no speed limit, also less traffic congestion, you can step the gas pedal to the base and engine power and fine chassis tuning can be fully utilized.

But in HK if you think and find seriously, you can still find some rds on which you can rush for some mintues with no worry about the traffic and police.

If you own a Porsche and want to test its performance power, you can participate in the Track Day at Chu Hoi (China) organized by some clubs several times in a year. Remember that furious driving on roads may result in trajedy not only to the driver but also to other road users.