Outdated Mach 5 Speed Racer 1.2

I managed to find a way to get the steering wheel to work
But I've come across a new issue, now the car won't go over 280MPH no matter the amount of power I put in it. Its nothing to do with the gearing as I already tweaked that and it definitely is not the engine as it produces a shitload of power, it probably has something to do with the aerodynamics or the version of automation I am using. Version 1.15 still works just fine but understand that the car may not be the same after this update. Also any information on how to fix this issue would help