I don't trust your 4.5 result. Are you saying that is the result you see from your logs? If your car will run the quarter in 12.4, your 0-60 should be quicker than 4.5. For example, based on a road test in C&D, a Mustang GT does 0-60 in 4.4 and runs the quarter in 13.0. I know damn well a tuned SHO will smoke a Mustang from 0-60. I have raced plenty of them and always walk away from them on the low end. They start gaining at about the 1/8 but can't quite catch me at the end of the quarter.
Where does the data come from that is on your log? Does it obain the speed from the car's ecu? I am not trying to be argumentative here but something is causing the 0-60 time you are seeing to be slow. What is your 1/8 mile time and speed? I think the drag times calculator is pretty accurate and will likely show your 0-60 under 4 seconds.