karachi is not bad over all, u should drive through the city, hope u like it, go to clifton and sea view, defense, drive on shahrah faisal and hope you enjoy..
i dont know if super highway is cautious place or not, if it is not, you can enjoy a long drive there and there are some very enormous restaurents there like al habib, where food is cheap and the best, as the weather is also good, u can have a max fun there... there is also a clean nice area called gulshan e maimar there, its very nice.
when i was in karachi i used to eat from hot and spicy in zamzama in defense, their tikka rolls are so tasty.. have fun..
i know u must be tired after the ride, but believe me karachi is one of the best places to visit in pakistan, it is a huge city and lots of places to visit esp the long drive inside the city