consider the title my own personal blessing/prayer, i can see this game making money as long as we have the word-of-mouth to spread it across the internet. thousands of gearheads and machinery techies exist all over the place, do not lose faith!
i understand my suggestions are not likely to be very feasible at this point, but i felt the need to voice them simply because i know it takes an active collection of thoughts to provide developers with well-constructed suggestions on which to base future development.
to the point:
i feel a need to simulate production of not only passenger-class vehicles, but also commercial-class workhorses. this idea requires little more than vastly different chassis, axle/suspension, and body styles; upscaling the potential size and design of engines; a mandatory diesel design which i see has been suggested already… simple and easy, right? 
in the nature of detroit (the GM company arm; not the game) it would seem reasonable to expect two-stroke designs, and the same array of forced induction that we have with the passenger class vehicles. needless to say, the design aspect will almost be like an entirely different game, and the company that the user creates must decide to become exclusively one or the other, or suffer the expense of a much larger dual operation.
these haulers can range from six-wheeler tiltbed wreckers or flatbed haulers, all the way up to eighteen-wheeler fifth-wheel semitractors. the transmissions would also need to be planned out and would likely be just fine with fixed-ratio, adjustable final drive design. since the game already has the design for gasoline engines, early versions of commercial rigs would also include thirsty, low-geared i6/v8 monsters that started as industrial castings and ended up as heavy forerunners to the modern electronically-controlled diesels that move our cargo on the roads today.
let me say again, i am not trying to demand this but rather trying to plant a seed in your mind as far as expanding the “tycoon” aspect of the game into logistics equipment as well as passenger vehicles. i am not sure how the economy for this will work, but the commercial side would prove to be interesting when you consider the different types of rigs used in different areas and applications.
would like to know how the developers feel about this. i can understand if it sounds like a lot of work. maybe just reading it will keep you both drifting around this idea as the game gets from crawling to walking?
again, kudos to taking the time to develop such a game, and good luck on reaching a target consumer base!
-kyle
