Forget Bmw's and Merc's even with a Jetta and Laura you can cruise around 140-150kmph with ease , such is the stability of those cars at those speeds! And if at all you have to brake all of a sudden you have the all wheel disc brakes , ABS , ESP and TCS to guide you.
But this doesn't mean having a fancy car you can push the car to its limits , more than driving faster driving safer is more important!