STs are 1060 kg here in Turkey. i don't know what makes the difference but i think it's a bit faster than yours, maybe...

kerb weight is the car's weight without any passenger and any cargo but full tank of fuel and other fluids.

gross weight is the maximum loaded weight; with maximum numbers of passengers and maximum of load limit.

if you get beyond this your car will suffer suspension, transmission and some other major problems. this is the upper limit...