Hah, freeways are the worst places to speed. You understand that the NCAP safety tests are done at 60km/hour right? If you crash into a pillar at 120km/h, you're gonna need airbags and Jesus. If you AREN'T being one of those irresponsible maniacs swerving between lanes through rush-hour traffic, the best you can do is enjoy speeding up from 100km/hour to 140km/hour, and then slowing down, and then speeding up again, and ... nah man.
I think the best fun in a reasonably fast car is the 0-60km/h dash from a traffic light: just watch out for pedestrians. And potholes. And traffic cameras. And cars not stopping from side-streets. And... yeah I dunno hey. Just be safe. Maybe get a step-up car from a Chevrolet Cruze to anything with a turbocharger. Even a 1.4T Audi or BMW 118i will feel great. Even an Opel Astra, I used to love those when I was younger! Anything but being a try-hard in a GTI.