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First, a quote that I didn’t get a reply to from the devs:

As I wrote. If we can’t have balance shafts (and I’m still not really convinced why we can’t), then at least please give us back the ability to affect the smoothness at least that little bit.

Now, I’ve done a second test (and I don’t know what did I change that the values are higher overall, as I don’t have these old test engines - and no, that’s not the matter of 4 valve vs 5 valve), to check other factors that can affect smoothness - here’s what I got:

Test 2.0 square:
Alsi, DOHC 5, 2016
2.0 square I4 (86.0 x 86.0 mm), 2016, DOHC 5, 6000 rpm redline.

Kee UE4 Change
in %
cast 0 0 51.7 49.3 -4.6
cast 0 40 50.5 48.8 -4.1
cast +10 40 60.9 53.8 -11.7
forged 0 40 58.5 51.4 -12.1
billet/titan 0 40 62.8 52.3 -16.7

Ok. So, let’s analyze that. First row - I get it, that’s the I4 and V6 smoothness nerf, I’m even surprised by how little the difference is. Second row also looks rather unsuspicious. But, for heaven’s sake, why do the next rows look like that? Why smoother engines got 3 up to 4 times bigger hit? Why it all just got averaged? Again, please give us back the ability to affect the smoothness that little bit.

That lack of ways to significantly affect smoothness further strengthens the I6s overpowered status, along with the modified engine bay limits. It harms the variety of approaches to run a successful company in the campaign.

Last but not least - why does smoothness affect reliability only after some artificially looking treshold of 25 smoothness? Isn’t 30 also low? Would all the precise components work as well in a shaky, 30 smoothness engine as they would in a nearly perfectly balanced 80 smoothness one?

If smoothness is important, why can’t we really affect it anymore? If it isn’t, then why you devs bothered with rebalancing it?


We changed the scale alongside the calculations and balance. You keep comparing the new values to the old scale, which started to give you problems when you dropped below the 50 smoothness mark.

I think your statement “give us back the ability to affect the smoothness at least that little bit” is ridiculous though. You have much more control over smoothness now than before, there are more strong dependencies, not less. Engine configuration and size does affect smoothness much more. Cam and VVT likewise. We have widened the scale to give you more meaningful choice, in different places to before, which seem to the the only ones you keep looking at for solutions. :slight_smile: In that sense I can understand your confusion.

The new system addresses three major issues the previous system just didn’t consider at all or to a too small degree:

  1. Some engines, when made large, are inherently terrible when it comes to smoothness. I3s over 1.5L and I4s over 2.8L, for example. For these configurations engines of that size or larger should not be feasible.
  2. Even the smoothest engines have bad smoothness when run with aggressive cam settings, unless they use VVT.
  3. Size matters a lot for inherently imbalanced configurations, but doesn’t in inherently balanced ones. I4 vs I6, the latter can easily be built at maximum size and still be quite smooth.

Balance shafts have been ruled out as a choice in the game, it adds complexity without adding much gameplay. They are part of the current engine configurations and get better over time. Hence why you can barely build a 900cc I3 in the 60s, but can make one reasonably smooth at 1.2L in modern times. I6s don’t improve that strongly because they don’t need balance shafts in the first place.

We revamped this game mechanic because it is so important, and the outcome is vastly superior to how it was previously. Perfect? Hell no, just much better than before and something you guys need to get accustomed to for sure.


It used to be the norm when engine smoothness below 50 is considered rough. What’s the approximate value now?


That now same displacement size but different bore and stroke values matter, but not much anyway. Can’t still make I4s over 2L smooth, even quality spamming them doesn’t do really much as you said. Forged/CNC crank doesn’t affect smoothness anymore, they used to increase smoothness significantly.


While I do not necessarily agree with your assessment of engine smoothness, here is what I will say. I noticed two big differences after the smoothness update:

  1. Making categorically stupid engines (eg Pontiac 195) is rather impossible. Whatever. As it should be
  2. The Premium and Luxury markets specifically are more recalcitrant than ever.

Its point 2 that is concerning because whatever the smoothness calculations are, they definitely seem to have made it impossible to make Premium / Luxury vehicles with anything other than straight-6s and V12s. Maybe this is a problem with the smoothness calculations. Maybe this is a problem with the market tastes. Maybe turbo tech is at fault. I don’t know but what I do know is that it that the Premium and Luxury markets were already difficult nuts to crack before the update even when taking after historical examples but they just seem downright rogue. Unless, that is to say, you use what seem like regimented engines for the purpose - straight-6s and V12s - which to @szafirowy01’s credit does seem to point to a problem with the smoothness calculations.

And just as a side, every other market in the game doesn’t seem to give a hot damn what engine put in the car as long as it its drivable and makes good power. Sometimes, all you need to do is make good power. This also seems wrong.


Nah man, not going to engage in an argument or answer questions like this where the other side assumes bad faith on my part, waste of my time.

Due to the points brought up, I will do is the following:

  1. Take a look at if the doubling up effect of comfort caring about smoothness and some luxury demographics caring about smoothness is too strong an effect. V8s should be perfectly viable options for the luxury segments, I4s not. @kmBlaine
  2. Have a look at if bottom end quality affects smoothness enough. @szafirowy01
  3. Take a look at if I can model the transition for smoothness being too low a little … smoother. @szafirowy01

Also I’d like to address @kalsylum question about how the scale changed. Basically the scale for the engine designer has shifted from 50 as the mid point to 25 as the mid point. That means instead of having a usable dynamic range of 50, we now have a range of 75. That allows for better mapping and balancing of the stat in general. The mapping is done for the demographics that care about smoothness and it looks like this:

The mapping.

Expand to see full list.

This is the data in the mapping graph. On the left is the input smoothness value, on the right is the “translated” desirability of that stat when it’s a demographic priority.

The effect of opening up the scale is to get more range to work with and a more meaningful progression. You see that the curve is the steepest at the low values and then flattens out. That means if you increase your engine smoothness from 45 to 50 that is much larger a jump than going from 85 to 90. So investing lots of money into making your V12 a little smoother is a bad idea, while doing the same thing for your I4 does make quite a difference in the end result.

The effect of smoothness on comfort currently is
SmoothnessFactor = (Smoothness / 60)^0.15,
which has its mid-point at 60 smoothness as you see (the point where luxury car buyers think the engine is adequately smooth), although the reference point really doesn’t matter to game balance much because everything is judged in the same way.

The smoothness factor could be toned down a bit if indeed it is too strong, just drop the exponent to 0.1 might be all that is required.



There are certainly a lot of new (and powerful) ways to decrease smoothness. I think @szafirowy01 is wondering why the ways to increase smoothness have been made less effective, although perhaps the rescaling to a midpoint of 25 does answer that to some extent.

Personally I think the new features are great, but when combined with szafirowy’s issue they definitely encourage the use of I6s and V12s even more than usual. Now it seems like the best way to design any non-sports car is to cram the biggest I6/V12 that you can fit and then adjust the components to match the desired PU/ET. There’s little incentive to choose a different configuration and then use engineering to bring the smoothness up to a desired level, which seems counter to real life.


Thanks @Killrob - you da boss.

It does seem a little too heavily emphasized in my opinion. While you’re definitely right that V8s were made much more viable for Premium / Luxury buyers than before, and yes that was definitely a noticeable change :wink:, I think moving the midpoint also had the side affect of buffing the straight-6s and V12s. And so the two sort of cancel each other out. Its not so much that V8s aren’t an option for making a desirable luxury car as it is just way easier to DnD min-max / stat whore it by using a straight-6 or V12.


I don’t know if in the current version V6s are too underpowered. They are always worse than I6s for longitudinal cars, the difference in desirability is noticeable, which is against the industry wide move from I6 to V6 IRL. There are lots of really smooth V6s out there.


The reason why the industry is moving towards V6s is mostly packaging.

I6s are inherently smoother but because they are really long they tend to not fit super well into transverse FWD applications, which has become the norm for a while now.


Packaging, weight, material cost, and for some reason the emissions were harder to deal with on an I6.

Edit: probably because of uneven air flow to the different cylinders.