It's a simple fact, the farther the pinion centerline is away from the ring gear centerline, as a percentage, the lower the mechanical efficiency. That's because there is more sliding of surfaces.

These are called hypoid gears. The inventor of the hypoid gear actually worked out the mathematics of the surfaces before building the first one. That flat boggles my mind. Before his invention, those right angle gear drives had the pinion centerline and ring gear centerline intersecting.

The hypoid gearset allowed car manufacturers to lower the driveshaft, thus lower the floor of the car.

Hypoid gearsets mandated the development of Extreme Pressure (EP or GL-5) gear lubes to deal with the sliding surfaces.

R.