Modeling of the automobile market
If the game uses historical data for its economic model, there will be a huge surge in demand for pretty much anything with wheels on it after WW2 which drops off after 1950, and a recession in 1958-62, smog controls in the early 70s, the infamous 1973 Oil Price Shock, and so on. If I as a player know my economic and regulatory history well enough, it'll take some of the challenge out of the gameplay. For instance, I know because I read Wikipedia that emissions controls will start to become mandatory in 1970 or so, and there's going to be a gas price spike in 1973. Armed with this knowledge, I do R&D on smog controls starting in 1960 and develop catalytic converters, and time the introduction of my new line of transverse-engine FWD compacts so that--just by purest coincidence, of course!--they hit the showrooms a day after the OPEC embargo.
To make it more challenging, you could have three difficulty settings:
-- pure historical, i.e., the 1973 oil price shock occurs right on schedule, with a 17% jump in the price of crude on October 16, 1973
-- a slightly tougher scenario where the general trends are the same but the timing and magnitude of events is randomized to a degree. The first time you play the game, the oil price jump is 10% and it occurs in January of '73; when you replay it the next time, it's 5% in September '74, or 33% in September '72, or something else entirely.
-- On the most difficult setting, the game starts with the 1946 economy and everything is randomized, so that, just like in real life, you can't tell what's coming next and having a detailed knowledge of economic history (or a good set of reference books) confers no special advantage.