I think if a car does 150km/h, it's pretty much acceptable.
Referring to the speed stakes, I drove hundai santro plus, 2001 model at 160km/h (Not safe for sure), Honda civic 2000 A/T @ 200km/h.
Currently driving Honda civic 1.5 Exi Manual and Altis 1.8 Cruisetronic, and didn't pushed both up to 160km/h and 180km/h respectively.
Over speeding is not at all safe for sure, though never felt it in my civic 2000 model, that's a beauty for sure.