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>So hybrids ended up as biggest polluting passenger cars in real world, when averaged. like the article itself, that statement is subject to a lot of condition

by trhway 6y ago

>So hybrids ended up as biggest polluting passenger cars in real world, when averaged. like the article itself, that statement is subject to a lot of conditions to the extent that it is meaningless without clearly stating all those conditions. For example, even without charging i average 48mpg on the previous gen Prius Plugin (and i do drive 85-90 on 237 - better aerodynamics results in very good mileage even at speed). You need very-very special setup, far-far from real world, for that to become "biggest polluting" .

zelos 6y ago
There's a difference between something like a Prius+ and the PHEVs mentioned in the article though: the BMW X5, Volvo XC60 and Mitsubishi Outlander are big, heavy SUVs, it's hardly surprising that they have poor emissions.
- trhway 6y ago
  if the implementation isn't screwed (sounds like a big if), they would normally have better emissions than their non-hybrid variants due to regenerative breaking (especially for big heavy cars) and better ICE burning modes (even if you use the same ICE, and much more improvement can be gained by making an ICE optimized for hybrid application). If the article is anywhere close to truth, then it can only be explained by the bad implementation - may be they moved the freed diesel engineers to do the hybrids after the dieselgate :) Recently walking a dog waiting for the light i saw/heard a Volvo XC90 hybrid doing ICE start from the red-light stop - the ICE started a moment before the car started to move - it did cross my mind back then that such start of engine would [unnecessary] burn a lot - ie. my Prius starts moving on pure electric with the ICE kicking, if/when needed, some moments later, much smoother, better torque and better efficiency. The performance-wise the XC90 had a regular start, far from anything fancy, and anyway large starting ICE wouldn't produce much performance while starting (and waiting for it to spin from the 0 in order to get some performance would eat the time thus killing that performance), so why would they do that ?
  - horstmeyer 6y ago
    They have to carry the batteries around which are heavy.
  - leetcrew 6y ago
    starting up an engine isn't nearly as "expensive" as people tend to think. engineering explained did a video on this, concluding that a warm start in a typical four cylinder engine uses about as much fuel as idling the same engine for only ~7 seconds. [0] kinda makes sense, since this is the whole motivation for start/stop systems in the first place. not covered in the video, but IIRC cold starts use quite a bit more fuel since the engine needs to run rich for a few minutes while it warms up. [0] https://www.youtube.com/watch?v=dFImHhNwbJo https://www.youtube.com/watch?v=dFImHhNwbJo
toyg 6y ago
> i average 48mpg on the previous gen Prius Plugin Man, I did 46 mpg with a VW Passat in 2018 (UK gallons tho)... Stats like these are disappointing.
- trhway 6y ago
  why? hybrid brings efficiency of the gas engine to that of the diesel (and better than that in the city) while being much cleaner. 15-20 years ago (the first years after coming from Russia where diesel was definitely a better option back then - and my father had diesel VW Passat there at the time :) i thought that the diesel was the way to go and was disappointed at California for the "anti-diesel" law, and only later understood that it was a right thing to do.
  - zelos 6y ago
    Also, people get confused with the efficiency of diesels, comparing MPG between petrol and diesel, when they're liquids with different densitites and carbon contents.
  - toyg 6y ago
    I just expected more by what was effectively the hybrid gold-standard (the Prius). My Passat was a regular diesel with some tweaks (VW called it "bluemotion"), thinking it got so close to the average hybrid efficiency made me slightly sad for a minute. But it's not important anyway, hopefully we're rapidly approaching an electric-first setup and that's what matters.
    - reportingsjr 6y ago
      You should really mention that it's diesel in a comparison like this. Diesels produce significantly more air pollution (particulary nasties like NOx) than similar gas/petrol engines.
- compsciphd 6y ago
  one thing to note is that there's a reason electric cars have lower range on the highway and gas cars have higher range. first thing to note: the faster you guy, the less efficient you can be (air resistance effects you to square I of speed I believe). So this explains, why electric cars get a lower range, the faster you guy, the more air resistance they have to overcome vs local driving with less resistance. but what about gass engines. This is simple: gas engines are inefficient. they can't be configured to produce exactly as much energy as needed (as opposed to a drawing from a battery). Therefore, at lower speeds, they are producing much more energy than is needed and it gets wasted. at higher speeds, even though they have to overcome the same amount of more resistance, much less energy is being wasted as more is needed. This has gone into why so much tech has gone into trying to make gas engines more efficient, from the prius's hybrid system, to stop/start to deactivating cylinders and on and on. how well did your passat do on local driving? my guess perhaps 2/3 of that number?

by trhway 6y ago

zelos 6y ago

There's a difference between something like a Prius+ and the PHEVs mentioned in the article though: the BMW X5, Volvo XC60 and Mitsubishi Outlander are big, heavy SUVs, it's hardly surprising that they have poor emissions.

trhway 6y ago
if the implementation isn't screwed (sounds like a big if), they would normally have better emissions than their non-hybrid variants due to regenerative breaking (especially for big heavy cars) and better ICE burning modes (even if you use the same ICE, and much more improvement can be gained by making an ICE optimized for hybrid application). If the article is anywhere close to truth, then it can only be explained by the bad implementation - may be they moved the freed diesel engineers to do the hybrids after the dieselgate :) Recently walking a dog waiting for the light i saw/heard a Volvo XC90 hybrid doing ICE start from the red-light stop - the ICE started a moment before the car started to move - it did cross my mind back then that such start of engine would [unnecessary] burn a lot - ie. my Prius starts moving on pure electric with the ICE kicking, if/when needed, some moments later, much smoother, better torque and better efficiency. The performance-wise the XC90 had a regular start, far from anything fancy, and anyway large starting ICE wouldn't produce much performance while starting (and waiting for it to spin from the 0 in order to get some performance would eat the time thus killing that performance), so why would they do that ?
- horstmeyer 6y ago
  They have to carry the batteries around which are heavy.
- leetcrew 6y ago
  starting up an engine isn't nearly as "expensive" as people tend to think. engineering explained did a video on this, concluding that a warm start in a typical four cylinder engine uses about as much fuel as idling the same engine for only ~7 seconds. [0] kinda makes sense, since this is the whole motivation for start/stop systems in the first place. not covered in the video, but IIRC cold starts use quite a bit more fuel since the engine needs to run rich for a few minutes while it warms up. [0] https://www.youtube.com/watch?v=dFImHhNwbJo https://www.youtube.com/watch?v=dFImHhNwbJo

toyg 6y ago

> i average 48mpg on the previous gen Prius Plugin Man, I did 46 mpg with a VW Passat in 2018 (UK gallons tho)... Stats like these are disappointing.

trhway 6y ago
why? hybrid brings efficiency of the gas engine to that of the diesel (and better than that in the city) while being much cleaner. 15-20 years ago (the first years after coming from Russia where diesel was definitely a better option back then - and my father had diesel VW Passat there at the time :) i thought that the diesel was the way to go and was disappointed at California for the "anti-diesel" law, and only later understood that it was a right thing to do.
- zelos 6y ago
  Also, people get confused with the efficiency of diesels, comparing MPG between petrol and diesel, when they're liquids with different densitites and carbon contents.
- toyg 6y ago
  I just expected more by what was effectively the hybrid gold-standard (the Prius). My Passat was a regular diesel with some tweaks (VW called it "bluemotion"), thinking it got so close to the average hybrid efficiency made me slightly sad for a minute. But it's not important anyway, hopefully we're rapidly approaching an electric-first setup and that's what matters.
  - reportingsjr 6y ago
    You should really mention that it's diesel in a comparison like this. Diesels produce significantly more air pollution (particulary nasties like NOx) than similar gas/petrol engines.
compsciphd 6y ago
one thing to note is that there's a reason electric cars have lower range on the highway and gas cars have higher range. first thing to note: the faster you guy, the less efficient you can be (air resistance effects you to square I of speed I believe). So this explains, why electric cars get a lower range, the faster you guy, the more air resistance they have to overcome vs local driving with less resistance. but what about gass engines. This is simple: gas engines are inefficient. they can't be configured to produce exactly as much energy as needed (as opposed to a drawing from a battery). Therefore, at lower speeds, they are producing much more energy than is needed and it gets wasted. at higher speeds, even though they have to overcome the same amount of more resistance, much less energy is being wasted as more is needed. This has gone into why so much tech has gone into trying to make gas engines more efficient, from the prius's hybrid system, to stop/start to deactivating cylinders and on and on. how well did your passat do on local driving? my guess perhaps 2/3 of that number?