Optimize for speed bonus as well. Depending on what you ship, it may be important to ship it fast rather than cheaply.
Although I am unfamiliar with pak192 comic, here are some examples from other paksets.
In pak64 you will barely make any money shipping passengers with a 120 km/h train in the year 2070. However if you use a 300 km/h train or faster there can be tons of profit to be made despite the running cost being several times more.
In pak128 you will make the most profit shipping milk at the fastest speed possible. Even though you can ship it at a fraction of the price with cheap slow convoys, the speed makes a huge difference to profit.
Speed bonus is in percentage revenue change per 10% relative maximum (not actual) speed change with respect to the speed bonus speed. This means that if a good has a speed bonus of 10% and you ship it at a maximum speed of double the current speed bonus speed then you will earn twice as much from it.