This is almost the same as the Lexus above, the LS430. You will see this car is only driven by the Collins' gang gang members. It has an excellent acceleration topped with an even better top speed, but the handling seems to make the car spin out of control at fast speeds and it is also quite weak so unless you're an expert driver, you probably won't be driving it for too long.
During Free Roam Mode and nearly every mission after the second, you will usually be blocked off by Soho boys driving this car. Soho boys usually make a small barricade to stop you from going, and the two gang members will get out of the car and try and kill you with their Ak47's. If you like the car they are driving, you won't enjoy it if you drive it when it's mashed up. I would recommend killing the gang members away from the Lexus if you're going to use it in the future; this being a very good idea as the SC430 is quite weak.
You will find this car most in the Collins' gang turf, Soho. It can be found anywhere around London but it is most common in Soho.