FreeGameDev

In the kart characteristics.xml file, the base unit power is ser"950", which seems to refer to the max power used by heavy-weight karts. What unit is the power being measured in? Watts, kW, HP?
I'm asking because I wanted to have one of my custom karts have similar engine, acceleration, and top speed characteristics to an actual vehicle.

I don't even know, because STK is not a simulation and although some element of the physics are rooted in real physical values (such as gravity), STK units are best understood as abstract units tuned for gameplay, not as real-world units. The speed and accelerations are only meaningful in relationship with the scaling of a track. Also STK doesn't accurately simulate real-world forces such as air friction, drag and others, too, so even if you tune engine, gears (they affect engine), acceleration and remove top speed caps, it still won't behave realistically.

Ok that's cool.