I know that I have come to this discussion somewhat late, but I should like to add some general thoughts on balancing philosophy if I may. Firstly, in my view, it is a mistake to have all vehicles have exactly the same value for money (having exactly the same ratio of purchase price to running costs to haulage capacity to maximum speed for each cargo type) because it makes the choice between different kinds of vehicles less interesting (and also less realistic). Some vehicles would be better value for money than others, and some, although worse value for money overall, would be more profitable in certain specialist situations (such as crack express trains, or short-haul bulk transport at slow speed, etc.). There should perhaps be an element of diminishing returns, in that paying ever more for a vehicle makes it better in increasingly small increments, the player having the difficult but interesting decision in every case where to stop. (The ideal manifestation of this would be to have several different price bands of vehicles all available at the same time, and then, as technology moves on, those same price bands applied to respectively higher specifications). There should also be a certain element of randomness: some vehicles should just be plain better than others (not necessarily be large amounts, but enough to make a difference). Again, this makes gameplay more varied and interesting, especially if players cannot rely on improvements in technology to be consistent.
Also, the game would be more interesting if the ratios changed over time. The trend in reality has been (very approximately) for newer vehicles to have higher purchase prices, but lower running costs and/or better performance. If this pattern was implemented in the game, the result would be a game in which both the risks and rewards slowly increased with the passage of time, starting out with it being fairly easy to make a small profit, but difficult to make larger margins, but becoming increasingly the case that, if one has the money to invest, and one manages the network well, one can make very considerable margins on newer vehicles, but there is a far higher risk of overspending and losing a very large amount of money quickly if one makes a mistake. That again would make the game more interesting.
Furthermore, I have been working on some patches to the main code which, if accepted, could make a real difference to how the paksets should be balanced. Further discussion can be found, amongst other places,
here, which also contains an initial version of the first half of the patch. (I am still working through some techincal problems on the second half). In essence, the function of the patches would be (1) to make the speed bonus (either positive or negative) have less and less impact the shorter the journey; and (2) gradually increase the maintenance costs of obsolete vehicles from the date of their obsolescence until (by default) 20 years after retirement. The cumulative effect of those changes would be to make differently balanced vehicles preferable for short-haul transport than are preferable for long-haul transport. There should be high capacity vehicles with low running costs but a low speed for short haul transport, but lower capacity vehicles with a higher top speed and higher running costs for long haul transport, since the earnings with short-haul transport would not vary much with speed, and so would benefit from capacity and low cost instead. These modifications would also mean that the speed bonus ought be set perhaps a little more aggressively than it is now, so that the speed that gets the 0% bonus is faster than the speed of the vehicles designed just for local transport (and is, perhaps, the approximate average of older but not obsolete vehicles designed for medium distance transport).
Finally, may I ask - are the British and 19th century vehicles available on addons.simutrans.com part of this great rebalancing? I always like playing with those vehicles, and it would be a great pity if they were not included.