well its not really fast, a wrx sti would be too much for a mustang gt from the stop, but on the highway i would lean toward the mustang,
civic turbo it would probably beat from a stop, on the highway depends on how much power the civic is putting out, its nearly impossible to get a fwd unmodded car to launch let alone one that has double the power.
cobalt ss would be about the same as the civic.
with 260 hp its not really a high speed car, newer cars are quite a bit faster, but its a different kind of power, it has probably double the torque of the cars you listed, and can cruise at 120mph with about 3000-3500 rpms... ( guestimate)
but on the other hand the aftermarket is filled with mustang stuff, spend a couple grand on it and blow them all away...