Quote:
Originally Posted by Joshdub
40x sounds like a big number, but what is the extent of that number? How does it factor into real world situations? Also, what is the trade off? Don't diesels emit less Co2 than gas cars, but higher NOx? Does the significantly better fuel efficiency (and everything that entails, from processing, to transport, to consumption) offset the higher NOx? Is 40x higher still cleaner than 10, 15, 20 years ago?
What is the BIG picture here? Everyone is just saying "omg NOx".
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Real world testing showed 10-35 times the standard. That testing was extensive. Some tests showed up to 40 times, and that is what the EPA announced. I went with 20 times in my example above, for lack of a better estimate.
The product development trade off is NOx vs (hp/fuel efficiency/torque/drivability - pick one or all)
A significant trade off for the manufacturer is cost. The cheat was most likely implemented to avoid the cost of things like SCR, while offering a product that consumers would adopt in greater numbers
No, higher NOx is not offset by greater fuel efficiency. If we wanted to do that calculation, you would have to do a human population health impact analysis. We know the impact of smog on annual deaths by country. There have already been calculations published of how many deaths in North America the VW emissions resulted in indirectly. For the fuel consumption/CO2 "upside" you would have to estimate the lives saved by the delay in global warming effects.
Diesels emit less CO2, which is why Euro vehicles tended to diesel engines (Euro rules have focused on CO2, at least up until now, but that is changing). Also, CO2 is related to fuel consumption, so CO2 is used as a proxy in Euro emissions regulations.
CO2 is a greenhouse gas, so the primary impact is on global warming and resultant climate change. NOx is a primary contributor to smog, which has more immediate health impacts in cities.
Europe is getting more worried about smog, and is coming up with NOx regulations. That will put a dent in the popularity of diesels in Europe, particularly if governments there decide to start taxing diesel fuel more like they tax gasoline, which is a real possibility. It all comes down to cost of ownership. A diesel vehicle with more expensive emissions controls, without government vehicle subsidies at point of sale to promote diesel industries, and without reduced fuel taxes relative to gasoline, has a hard time competing with a gasoline engine or alternate fuel. That is why this all matters, diesel was a gamble that Euro manufacturers bet on, and which they now have to reconsider. Some may already have done so; look at how BMW is promoting the i3 and i8, relative to their diesels (at least in some markets).
Consider that most diesel vehicles have been sold with tax breaks (subsidies) that were passed on to purchasers. Governments have started claims against VW to get those tax breaks back for the past years of fraudulent sales.
I keep hearing about the EPA, but US vehicles represent only 4.5% of the problem for VW. A drop in the bucket. The future will be played out on a larger stage IMO.