Top speed right at 80 mph. 0-60 right around 30 seconds. Maximum HP at around 5000 rpm. They will run 55-65 fine, though the engine is not exactly quiet. Interstates at 75 mph is working the engine pretty hard though. Also, the faster you go, the higher the engine temperature goes. If you drive in the summer heat for extended periods, 75 mph will cause the temps to rise to near unacceptable levels.

If the car has air conditioning, you may also have overheating issues as the radiators are big enough for the engine but not much more.