After the update I noticed two issues (at least I think it is not intentional) for older cars.
Buyers tend to have very high comfort expectations now, especially until 1990 in relation to my cars.
A 1985 Sedan with all premium interior barely passes the buyers taste in comfort for an average family car. Sure, it has firmer suspension tuning, but for a family sport it has a painful comfort penalty. Please have a look into it.
The other thing is that in the real life counterparts, emission restrictions were not a thing before 1975. The only area where earlier laws (WES applied) make sense is Ariya (Japan) which doesnt exist yet in the game. This can be frustrating since before converters (outside USA they didnt appear prior to the mid 1980s) you don’t have that emission optimization tab and your car fails in campaign unless you build something way more advanced than real engines were back then.
Emission laws became stricter exponentially starting in the 80s (70s in USA) but not linear starting in 1960.
I am not 100% sure what emissions optimization is supposed to represent, but to me it would make sense to be able to use it without cats. Lots of pre-cat engines had stuff like EGR, puls air, smog pump etc. to pass the early restrictions.
In the current implementation, emissions optimization affects the fuel map. Starting from the bottom left (low RPM/low throttle) and covering a wider area with each level, it sets Lambda to 1.0 (IE stoichiometric AFR, or not lean, not rich). The purpose of this is to allow the catalytic converter to be as efficient as possible, and it’s not particularly valuable otherwise, or at least that’s the idea I think. As far as I can tell all other emissions devices are basically implied to be part of the fuel system (type and quality).
Not sure about the emissions, but the very low competetiveness has been solved with the third patch. It´s not as easy as in the stable release, but definitely now a lot better balanced and seems just right. In this aspect, a huge step foward.