Cruising RPM <-> cabin noise, smoothness

[Packbat]

Engines make more noise and vibration at higher RPMs. That implies to me that a car with a lower cruising RPMs (60-70 mph in economy cruising gear) will be quieter and smoother during highway cruising than a car with higher cruising RPMs. Would it be possible to incorporate this gearing effect into the game? I'm imagining calculating the engine noise and smoothness for the same RPMs the game uses in the economy calculations, and averaging those values into the listed smoothness and noise of the engine to get an average in-use engine noise and smoothness - adding Comfort for cars with a lot of overdrive relative to sportier, higher-revving vehicles.

[chema1994]

It would make an Overdrive useful just not for fuel economy.

[Killrob]

That is an interesting point for sure. Before we get into implementing such a thing though it would be reasonable to establish that sports cars indeed have too high comfort ratings and comfort cars too low comfort rating I don't think that can be done yet (but soon-ish).

[Packbat]

Cool - thanks!

[ArnRno]

I was going to make a new topic for this, but I think piggybacking it here is just as good -

I had a similar thought this week, and I wanted to know if, like cabin noise and smoothness, gear selection/rpm could affect vehicle reliability.

If I were to make a decently sporty car, and gear it more towards the short end, I could end up having the cruise rpm quite higher than if I use that same motor in a tamer vehicle. I could have a very high reliability score for the motor, but if I have a 6k redline, and I'm doing 5k @ 70mph compared to 2900 rpm on another application, then I feel that I would definitely make that vehicle overall less reliable (all other things being equal, eg. different trim with just a gear change), and definitely decrease the MTBF.

Granted, I did use a rather large and unrealistic difference in the example, but it gets the point across - if a 3100 rpm difference would affect it [X] amount, then an 800 rpm difference should still have some affect as well.

Lastly, if this is already in effect, then sorry, oops, I just didn't notice - I haven't gotten around to checking for the change yet.

[Killrob]

Interesting point, but I think other aspects are killing that kind of thing already: too short ratios will give a sporty car like this too low top speed and too low acceleration, resulting in worse sportiness and prestige values. I don't think a build like this would be viable anyway.

[nialloftara]

That example is a bit extreme, but the difference in highway manners, and mpg between my 3.722:1 final gear '92 corolla and the 4.31:1 '06 scion xb, both with a curb weight around 2400lbs and roughly 105hp is very pronounced. It definitely detracts from comfort if I have to cruise at 60 turning 3000 rpms when I used to do it at 2700.

[ArnRno]

It was definitely extreme, but it illustrated my point well. I went from 3.08 to 3.55 in my old XJ and noticed a bit off a difference, but between the 3.23 to 4.11 in my Mustang, I noticed a much larger one - first gear in the Ford became basically useless past 9mph,

The more I think about it though, the more involved the equations become - Technically cruise speeds could differ between markets, depending on national speed limits. Also, cruise rpm could change for a give speed depending on terrain - for instance, I sometimes take a drive to San Francisco from where I am, and instead of cruising at 60ish mph in 5th, I have to climb mountain interstates, so I'm doing 60 in 4th, or 50 in 3rd... I'm making it more complex then it needs to be, but it is a real world possibility, we all drive differently.

I think that cabin noise/ comfort/ vibration, ie, NVH, as well as reliability should all be affected in some way by RPM, but damn, we threw a bit of a curveball at the devs with this one, so I am curious to see what pans out.

[Packbat]

Bumping this because I had a thought: the game currently has a list of RPMs that it calculates for fuel-economy purposes. Using the same RPMs for comfort and reliability seems like a sensible hack - they're all supposed to represent day-to-day use, after all.

[ArnRno]

One thing that bothers me in the fuel econ/ cruise RPMS listed is basically gear choice -

Sometimes... Okay, A LOT of the time the gear choice is just... wrong.

Great, the calculations find that, according to this magic world of Automation, my car gets great mileage, but when I look at the breakdown, my eco-box is doing ~15mph in 5th gear. 5TH GEAR @ around 1000 RPM with an 80hp four, etc - I might believe this if Automation was a Peterbilt simulator, but it isn't. Who shifts into fifth gear before they even cross an intersection? No one. More than being something people don't really do, it's something a car can't really do - I'm a pretty big fan of 4-cylinder cars, and I'm not talking about performance models here, I'm talk about everyday go-to-work cars here, cars with engines that make single-digit power at around 1000 RPM. Take my Impreza even - tons of horsepower, 160hp peak, but the motor will do nothing except lug below about 1500/1600 RPM.

Another thing about the fuel econ gear choice thing is that I'll notice pretty often is that the gear choices for the econ test are again, so far from real life, and then they get worse by changing there mind halfway through the tests - it'll look like:

15mph @ Whatever RPM in 3rd Gear <----- Short shifting already, okay, let's go for mileage.
25mph @ Whatever RPM in 5th Gear <----- Wow... I'm sure that car is really moving with all 17 ft/lbs you're making there...
45mph @ Whatever RPM in 5th Gear <----- Looks like we're in top gear now, let's keep those revs low and mpg high...
55mph @ Whatever RPM in 4th Gear <----- Wait... Why did you downshift???
75mph @ Whatever RPM in 5th Gear <----- Just to shift back up again? Is this your first day?

Obviously, different cars are different, but something is really off with how the system is going about it right now. I know it just sounds like I'm complaining, but I can't code to help out, so all I can do is give my feedback. I do concede that the program is more intelligent than I am, I'm nearly certain, but Automation hasn't ever driven a car in the real world, which is what we're trying to make here, right? Whether the cars are average or not, the buying public (especially for the market I mentioned) are average drivers, not race car drivers, or hypermilers.

Also, sorry, this is sort of the wrong thread again...

[Packbat]

I don't know if it's the right thread, but I agree that it's odd behavior.

...it might be a minimum power thing. Maybe at 45 in 5th it has enough power to overcome air resistance, but at 55 in 5th it doesn't, so it downshifts? That suggests a couple ideas to my mind:

• Have an acceleration requirement for each gear adding to the required power in that gear. If you look at regulations on speed change lanes, there's an assumption about a minimum acceleration that the car will be capable of (and that's with a lot of breathing-room added in). Just plugging in the numbers and distances very quickly for a 1000 kg car accelerating from 50 to 90 kph over a 125 m distance, I estimate a car would need 33.6 kW = 45 hp over and above the wind resistance at those speeds.
• Calculate gearing from the top down. Start at 120 kph (the highest fuel-economy calculation speed) and determine the cruising gear, then with each step down (90, 70, 50, 30) check to see if the car can stay in that gear or if it needs to downshift. Do not check if it could get away with upshifting.

I would also suggest having a minimum-RPMs check on the gear choices, but that's probably implemented already.

Edit: This might mean calculating two RPMs for each gear: cruising and acceleration. Something to consider.

Edit Mk. 2: A car that doesn't have enough power (edit: or gearing) to carry out all the maneuvers should probably have a Drivability penalty - being much slower than the speed of traffic causes accidents.

Edit Mk. 3: ...a year-dependent penalty, as cars in earlier years were not expected to perform the same maneuvers as cars are today.

Edit Mk. 4 (okay, I promise I'll stop): Actually, never mind - implement it like the fuel availability penalty to desirability, where a car is less desirable in the markets in places where it's too slow.

[Killrob]

Gear choices are properly calculated and take into account all kind of drivetrain losses, rolling resistance, air resistance, throttle inefficiencies and very importantly the engine efficiency and power at certain RPM. So what ArnRno observed there could be due to the engine in his example is being tuned for higher RPM, so at low speeds it just takes the low RPM position to minimize throttle inefficiency, while when getting up to speed allows to shift down where to get to revs where the engine is reasonably efficient and doesn't incur too much closed-throttle losses.

Your point about "Automation has never driven a car" is as valid as it is invalid. Modern economy testing procedures have never driven a car either and those produce the numbers you read in car specs. Not necessarily representative of real life.

The only point I fully agree with is the low RPM numbers, which already has been fixed in the closed beta by just upping the lowest possible RPM value to 1.5x engine idle from currently 1.2x engine idle.

[Killrob]

Edit Mk. 2: A car that doesn't have enough power (edit: or gearing) to carry out all the maneuvers should probably have a Drivability penalty - being much slower than the speed of traffic causes accidents.
Edit Mk. 3: ...a year-dependent penalty, as cars in earlier years were not expected to perform the same maneuvers as cars are today.
Edit Mk. 4 (okay, I promise I'll stop): Actually, never mind - implement it like the fuel availability penalty to desirability, where a car is less desirable in the markets in places where it's too slow.

2) Yes, have you watched the LDUs recently? That's in the next update.
3) ditto
4) can't be done yet because of the regions not being fleshed out yet, but the game does take that into account in the next update.

[Packbat]

2) Yes, have you watched the LDUs recently? That's in the next update.

Aha! Sweet!

(Apologies for the redundancy - I've not been in great health lately.)