Author Topic: Insane overengineering of a car headlight  (Read 18008 times)

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Offline tooki

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Re: Insane overengineering of a car headlight
« Reply #125 on: April 03, 2022, 09:03:54 pm »
I was not suggesting they don't feel good - rather that they make inferior choices for fuel efficiency when confronted with real world hills, not idealised test tracks and driving around Heathrow airport. However, they're still far better than the average driver.
Sorry, can you clarify what you’re actually claiming? “Inferior choices” doesn’t tell me anything, since what’s “inferior” depends on what you’re optimizing for.

Just state in plain English what you think they’re doing wrong.
 

Online Monkeh

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Re: Insane overengineering of a car headlight
« Reply #126 on: April 03, 2022, 09:05:34 pm »
I was not suggesting they don't feel good - rather that they make inferior choices for fuel efficiency when confronted with real world hills, not idealised test tracks and driving around Heathrow airport. However, they're still far better than the average driver.
Sorry, can you clarify what you’re actually claiming? “Inferior choices” doesn’t tell me anything, since what’s “inferior” depends on what you’re optimizing for.

Just state in plain English what you think they’re doing wrong.

Was 'fuel efficiency' not clear? Behaviour I've encountered includes both unnecessary low gear usage and holding on to a high gear far too long, resulting in violent downshifts to maintain any sort of reasonable speed.

Anyway, it's my opinion that they're not as well optimized for terrain I have to deal with as some think. I do not have six pages of precise data to back it up, so sorry.
« Last Edit: April 03, 2022, 09:07:15 pm by Monkeh »
 

Online coppice

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Re: Insane overengineering of a car headlight
« Reply #127 on: April 03, 2022, 09:08:31 pm »
An automatic dual-clutch transmission is just as efficient as a manual transmission.  Arguably it is even more efficient because it can swap gears more quickly due to the built-in rev-matching, which leads to less time when the clutch is slipping or when no power is applied (fuel burn but with no output.)  That's especially important for city driving, but when on the highway roughly all automatic and manual transmissions behave similarly, due to most modern automatic transmissions having a lockout for the torque converter.
A modern torque converter transmission is just as efficient as a DCT at speed, because they lock up the transmission, bypassing the torque converter. Both tend to be more efficient than a manual at speed, because they have more gears to choose from. A manual with 8 or more gears would be pretty tedious to use, but its now normal for automatics.

Around town torque converter automatics have always performed well. The losses in the torque converter are offset by the narrow band CVT like nature of a torque converter automatic, filling in between actual gear ratios.
 
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Online coppice

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Re: Insane overengineering of a car headlight
« Reply #128 on: April 03, 2022, 09:13:06 pm »
I was not suggesting they don't feel good - rather that they make inferior choices for fuel efficiency when confronted with real world hills, not idealised test tracks and driving around Heathrow airport. However, they're still far better than the average driver.
Sorry, can you clarify what you’re actually claiming? “Inferior choices” doesn’t tell me anything, since what’s “inferior” depends on what you’re optimizing for.

Just state in plain English what you think they’re doing wrong.

Was 'fuel efficiency' not clear? Behaviour I've encountered includes both unnecessary low gear usage and holding on to a high gear far too long, resulting in violent downshifts to maintain any sort of reasonable speed.

Anyway, it's my opinion that they're not as well optimized for terrain I have to deal with as some think. I do not have six pages of precise data to back it up, so sorry.
Any issues with uphill driving respond well to kickdown. I find the main annoyance with modern automatics on hills, is when going down hill. The car detects its inclination, and often changes down to apply engine braking on a steep downward slope, but it can be rather quirky. I usually apply some manual nudging of the gearing in such conditions.
 

Online tom66

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Re: Insane overengineering of a car headlight
« Reply #129 on: April 03, 2022, 09:44:58 pm »
Was 'fuel efficiency' not clear? Behaviour I've encountered includes both unnecessary low gear usage and holding on to a high gear far too long, resulting in violent downshifts to maintain any sort of reasonable speed.

Anyway, it's my opinion that they're not as well optimized for terrain I have to deal with as some think. I do not have six pages of precise data to back it up, so sorry.

I'd be curious what automatics you've been driving.

Certainly, my Golf's automatic really hates the low gears.  At 30 mph it's often in 4th or 5th, and above 40-50 mph it's pretty keen to get into 6th.   It often even starts off in 2nd if you're on a slight downhill slope (the gearbox has an angle sensor; it's reported in the diagnostics data.)  In some situations, it'll do that if the 1st gear clutch is getting too warm, for instance lots of city driving, with a corresponding boost to engine rpm to make the start in 2nd less aggressive.  I've never had it happen, but apparently if one of the clutches totally fails, then it'll just start using the alternate one in a limp-home mode fashion with limited power.

On a side note, it's quite interesting to see how the VW gearbox manages clutch slippage.  I have had a few instances where the car began to judder ever-so-slightly at low speeds, indicating it's slipping the clutch a bit too little, but after doing this for more than a few moments, it learns pretty quickly where the new bite point is.  Bite points are calculated with a kind of multi-point linear mapping, so it has a point for (e.g.) 10Nm, 20Nm and 50Nm as well as fully engaged.  During parking maneuvers, the engine acts as a constant torque source, with the clutch slipping as needed.  If you apply the brakes during operation, it seamlessly begins to withdraw the clutch to balance the brake, engine and clutch forces to reduce the output torque to the user's request. 

I know it's totally obsolete for electric vehicles (and indeed, when my car is in the fully-electric mode, any time the battery has more than the minimum-state-of-charge, it does not do any of this complex behaviour, instead, it uses only the electric motor with the clutches fully closed.)  But, you really do have to appreciate the engineering required to make an ICE-powertrain behave as smoothly as it does. 
« Last Edit: April 03, 2022, 09:47:59 pm by tom66 »
 
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Offline Bassman59

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Re: Insane overengineering of a car headlight
« Reply #130 on: April 05, 2022, 01:08:07 am »
You can add automatic versus manual transmission to that list these days. I know there are purists out there who will argue that manual transmissions give them "greater control" over the vehicle, which is just bollocks in my eyes, but the fact remains, a well designed modern automatic transmission is better than old manual boxes in every way, including fuel economy.

The cost to maintain and repair a modern automatic transmission greatly exceeds same for a manual transmission. We had a 2011 Jetta Sportwagen TDI (which was later bought back by VW) and it was offered in a six-speed manual and a fancy automatic. The scheduled maintenance for the automatic was easily over $1,000. For standard maintenance, not repair. Now everyone knows there's a VW tax because every service is expensive, but that was out of line. That was one reason for buying the manual. The other reason is pure preference.
 

Online tom66

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Re: Insane overengineering of a car headlight
« Reply #131 on: April 05, 2022, 07:27:11 am »
That is out of line.  Maybe VW America has different service pricing and schedules.

The service schedule for the DSG box in my car is 40,000 miles / 4 year DSG oil change.  At a main dealer that's £320 (~$420USD) but at any good independent it's as little as £200.   Or, you can do yourself pretty easily, though it will require a diagnostic tool (~£100) to activate the gearbox pump so you can totally drain the old oil.

The big expense is the gearbox oil.  VW recommend a type that is used only for a few other models, and since it is used to lubricate the solenoids and provides the wet-clutch interface, I'm therefore skeptical about replacing it with traditional ATF.  6 litres of the stuff will cost £140, most of the cost of the service...
 

Offline tooki

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Re: Insane overengineering of a car headlight
« Reply #132 on: April 05, 2022, 05:27:31 pm »
In USA, German cars are treated as semi-luxury vehicles (and the manufacturers often encourage this by only offering higher end configurations in USA), with parts and service being far more expensive than they should be. :/
 

Offline Someone

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Re: Insane overengineering of a car headlight
« Reply #133 on: April 05, 2022, 09:54:06 pm »
In USA, German cars are treated as semi-luxury vehicles (and the manufacturers often encourage this by only offering higher end configurations in USA), with parts and service being far more expensive than they should be. :/
Alongside an outdated culture in the US to change oil very often:
It used to be normal to change the oil every 3,000 miles, but with modern lubricants most engines today have recommended oil change intervals of 5,000 to 7,500 miles. Moreover, if your car's engine requires full-synthetic motor oil, it might go as far as 15,000 miles between services!
"might go as far" (with a qualifier to limit the applicability) vs manufacturer warrants it will go at least that far, bordering on misleading. Synthetic motor oil? same price as the rest here.

European cars tend to cluster their oil intervals at the higher end 10,000km or 20,000km and 1-2 years between oil change, while some manufacturers like Subaru say every 6 months!
 

Offline Ed.Kloonk

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Re: Insane overengineering of a car headlight
« Reply #134 on: April 06, 2022, 12:22:57 am »
In USA, German cars are treated as semi-luxury vehicles (and the manufacturers often encourage this by only offering higher end configurations in USA), with parts and service being far more expensive than they should be. :/
Alongside an outdated culture in the US to change oil very often:
It used to be normal to change the oil every 3,000 miles, but with modern lubricants most engines today have recommended oil change intervals of 5,000 to 7,500 miles. Moreover, if your car's engine requires full-synthetic motor oil, it might go as far as 15,000 miles between services!
"might go as far" (with a qualifier to limit the applicability) vs manufacturer warrants it will go at least that far, bordering on misleading. Synthetic motor oil? same price as the rest here.

European cars tend to cluster their oil intervals at the higher end 10,000km or 20,000km and 1-2 years between oil change, while some manufacturers like Subaru say every 6 months!

Some mechanics do profess the benefits of regular oil changes. Even if they are in the servicing industry, the point they make is neither the interval nor the miles driven is entirely precise. It depends on the condition of the oil itself. When it's time, it's time.

« Last Edit: April 06, 2022, 03:29:27 am by Ed.Kloonk »
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Offline Someone

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Re: Insane overengineering of a car headlight
« Reply #135 on: April 06, 2022, 01:48:43 am »
In USA, German cars are treated as semi-luxury vehicles (and the manufacturers often encourage this by only offering higher end configurations in USA), with parts and service being far more expensive than they should be. :/
Alongside an outdated culture in the US to change oil very often:
It used to be normal to change the oil every 3,000 miles, but with modern lubricants most engines today have recommended oil change intervals of 5,000 to 7,500 miles. Moreover, if your car's engine requires full-synthetic motor oil, it might go as far as 15,000 miles between services!
"might go as far" (with a qualifier to limit the applicability) vs manufacturer warrants it will go at least that far, bordering on misleading. Synthetic motor oil? same price as the rest here.

European cars tend to cluster their oil intervals at the higher end 10,000km or 20,000km and 1-2 years between oil change, while some manufacturers like Subaru say every 6 months!
Some mechanics do profess the benefits of regular oil change. Even if the are in the servicing industry, the point they make is neither the interval nor the miles driven is entirely precise. It depends on the condition of the oil itself. When it's time, it's time.

Code: [Select]
Cadogan Video: [url]https://www.youtube.com/watch?v=TuiVdQWGmWI[/url]
Cadogan is usually immaculately accurate on automotive topics, but actually stumbles a little on this one. Servicing periods do have a tolerance/limit to them, and its not usually not the publicly stated service interval (which he says is a hard absolute maximum limit). Like I point out in the quote above, a little emotional sleight of hand pushes people to replace their oil more frequently than the manufacturer actually recommends. Going on into "well its actually more flexible and depends on the specific history/operation of the vehicle" is trying to take a bet both ways.

Time limits: largely humidity absorption in these situations, but also material outgassing/absorption. Both dependent on temperature. Some manufacturers vary these by region where the car is sold.
Distance limits: accumulation of byproducts/wear/contamination. Set by worst warrantable conditions (go worse and they say it was abuse of the vehicle, example: stop-start batteries in taxis/courier vehicles).

Cadogan discusses a stop/start short distance car driven many times a day as far more damaged over distance travelled than a grand cruiser only doing the occasional country drive, but to keep warranties safe the oil is usually still mandated replacement on schedule. Some newer cars are accumulating "wear" on the oil at differing rates for different conditions and bring up the oil change indicator at a different rate. DPFs on Subaru diesels are very picky about contamination (again mentioned in the video) but they are still an accumulated damage, so its only a statistical prolonging of life by sticking to the set schedule. Its not guaranteed to get a certain life, everything in modern automotive is engineered to last sufficiently long for warranty/consumer protection. Many approximations and guesses are involved, its not a hard limit.

Plenty of vehicles (treated carefully/well) will be seeing little to no degradation by going over the set time limits, but when testing for the physical limits is more expensive than replacement, things just get replaced. Heavy vehicles with huge volumes of oil are economic to test for life extension, small cars not so much (good luck getting appropriate test limits for a light vehicle out of the manufacturer).

Also much of the limits are set by the manufacturer before the car is released (rarely do they update them after sale), which for new designs might have very little historic data to back it up. Once a design has been out in the wild for a decade the mechanics start to see patterns of what was either too lax or too restrictive. I know a specialist car mechanic who adjusts the schedules away from the factory figures, some go longer, some go shorter. But only once they are out of manufacturer warranty. The same engine model, with the same line item service parts can see different schedules in later facelifts or models of car (again up or down). Do I watch those things and change the service intervals based on the new data, absolutely! Will the manufacturer suggest you change? No.

* blimey, the forum aggressively embeds youtube links!
« Last Edit: April 06, 2022, 01:52:52 am by Someone »
 
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Offline Ed.Kloonk

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Re: Insane overengineering of a car headlight
« Reply #136 on: April 06, 2022, 03:39:18 am »

Cadogan is usually immaculately accurate on automotive topics, but actually stumbles a little on this one.
It's a vid from 2018 and I noticed the comments are turned off so the inevitable pie-chucking must have ensued.

Quote
Servicing periods do have a tolerance/limit to them, and its not usually not the publicly stated service interval (which he says is a hard absolute maximum limit). Like I point out in the quote above, a little emotional sleight of hand pushes people to replace their oil more frequently than the manufacturer actually recommends. Going on into "well its actually more flexible and depends on the specific history/operation of the vehicle" is trying to take a bet both ways.

I do kinda sorta like the Subaru attitude: We put the effort into engineering a fine engine. You, the owner can make the effort to keep it that way.
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Online tom66

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Re: Insane overengineering of a car headlight
« Reply #137 on: April 06, 2022, 08:08:06 am »
I'm not clear on how it works, but my Golf has an 'oil quality indicator'.  Last I checked after a service it read 'Good'.

I notice that when it reads 'Acceptable' (I have never got it to read 'Poor') the engine runs on the cold cycle much longer - i.e. the first start will not allow the engine to shut down for a good 2-3 minutes, whereas 'Good' oil will reduce that to 30 seconds. 

Perhaps it's just based on time-since-service, but given it's a hybrid, I wonder if there is some way to meter the quality of the oil, like the time required for oil pressure to build up on start, or if there's a turbidity sensor somewhere in the pan. 

As you say @Someone it's all based on statistics, I can floor my car from cold and get the 148hp engine to produce full output, but I would be an idiot to do that... I suspect if I did that every morning, the car would never meet its warranty limits,  but then again,  most people don't drive like that.
 

Offline Someone

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Re: Insane overengineering of a car headlight
« Reply #138 on: April 06, 2022, 10:43:42 am »
Perhaps it's just based on time-since-service, but given it's a hybrid, I wonder if there is some way to meter the quality of the oil, like the time required for oil pressure to build up on start, or if there's a turbidity sensor somewhere in the pan.
There might be something more complex in newer cars, but the "basics" have been around for a while, far beyond just counting cold starts:
"Self-Study Programme 224 Service Interval Extension"
http://www.volkspage.net/technik/ssp/ssp/SSP_224.pdf
Estimating remaining life from: fuel consumption, time @ temperature accumulation, and distance. Then producing some state estimators for the physical characteristics of the oil (not actually measured in the car) and predicting life from that.
 

Offline Bassman59

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Re: Insane overengineering of a car headlight
« Reply #139 on: April 06, 2022, 04:54:30 pm »
I'm not clear on how it works, but my Golf has an 'oil quality indicator'.  Last I checked after a service it read 'Good'.

My Honda Fit and CR-V hybrid both have "oil life" indicators, given in percent. The lifetime doesn't correlate with mileage, as far as I can tell, and the reading I've done says that the lifetime is a function of many variables including temperature, type of driving (city vs highway) and length of trips. Daytime desert driving in 46ºC outside temperatures surely has an effect on oil life. Anyway, when the indicator hits 5% I make a mental note to call my local independent garage for the service.

I've had the CR-V for nearly a year (I don't recall the mileage offhand) and the indicator just flashed 15% lifetime remaining.
 

Offline Bassman59

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Re: Insane overengineering of a car headlight
« Reply #140 on: April 06, 2022, 05:01:46 pm »
That is out of line.  Maybe VW America has different service pricing and schedules.

The service schedule for the DSG box in my car is 40,000 miles / 4 year DSG oil change.  At a main dealer that's £320 (~$420USD) but at any good independent it's as little as £200.   Or, you can do yourself pretty easily, though it will require a diagnostic tool (~£100) to activate the gearbox pump so you can totally drain the old oil.

Here in the US, the service departments are the big moneymakers for dealerships. This is why dealers fight to keep service information out of the hands of independent garages and car owners.

But, now that I have thought about it: yes, the service interval for the DSG was 40,000 miles or 4 years. The dealer offered free oil change services for the first three years, and then the fourth year would be that $1,000 DSG/etc service. Since I bought the manual transmission that service was not necessary and the independent garage across the street did the standard service for not much money. (Dealer charge was double the indie.)

Seriously, though, here in the US, Volkswagen parts and service are much more expensive than equivalent service for a Japanese or a domestic car.
 


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