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Comment by ummonk | Hacker News Reader

>To think that cars could use diesel engines, be cost-competitive with gasoline-fueled alternatives, AND pass the ridiculously-low emissions standards that lawmakers have arbitrarily decreed was simply wishful thinking.

The emissions standards are perfectly sensible for maintaining good air quality. It definitely looks like it is wishful thinking for diesel engines to meet those standards and be cost-competitive with gasoline-fueled alternatives, but there is nothing wrong with that. Gasoline engines may simply be the more suitable technology for passenger cars.

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> It definitely looks like it is wishful thinking for diesel engines to meet those standards and be cost-competitive with gasoline-fueled alternatives

The technology that would have brought "Dieselgate" diesels into compliance with EU emissions rules was said to cost manufacturers something on the order of US$100 per vehicle: Selective catalytic reduction (SCR) with a refillable AdBlue (urea) tank.

However, prior to Dieselgate there is alleged to have been collusion between the major German automakers and a secret agreement not to install it on small vehicles.

This collusion, rather than the emissions cheating itself, is the focus of ongoing criminal investigations in Germany. (Cheating on emissions tests itself was not actually illegal in Europe, because the legislation was created with loopholes).

As of 2019, AdBlue is becoming common on new small diesel vehicles in Europe.

The Euro6 standard was launched back in 2014, following the Euro4- and 5 standards that most of the diesel-gate cars adhered to. Most cars manufactured from around 2016/17 are Euro6, and as far as I’m aware Urea tanks are in use on most or all.

I honestly don’t understand why it would have been an issue to have it before. My diesel tank is 65L and it takes me over 1000km. Even if they had made a 10L Urea tank and shrunk the gas tank to make room for it, the range is still more than enough. Filling it takes 5 minutes once every 1-2 years and costs about the same as windshield wiper fluid. Can’t see why that would make the car unappealing either.

> Filling it takes 5 minutes once every 1-2 years

Isn‘t this a part of the problem? The urea tanks are way too small and need refilling way too seldom which means a too low urea usage? Volkswagen wanted urea to be refilled by your service station and not by the customers themselves because they might have found this inconvenient.

Exactly. If it's only being filled with (eg) 8L every 1-2 years, then it's not being used much and is probably not very effective at reducing NOx emissions.

Depending on the engine, driving style, etc, it should really be using something on the order of 20-60 litres of AdBlue per 1000 litres of diesel.

My last car was a diesel-gate car (09 Audi) which didn’t have a Urea tank at all.

I know VW managers first thought Urea was an inconvenience to have at all, then an inconvenience for owners to refill so should last a service interval. My new car has a Urea tank and isn’t a diesel-gate car. It need to refill maybe 1 time before the service intervals. I can’t see why it would be considered inconvenient - it’s easier to refill than windshield wiper fluid (that you need to pop the hood for!). So if it would have come at a price of 20L diesel capacity space, and require refills every month, I still wouldn’t have found it inconvenient.

I don’t know how they determine how much AdBlue to consume now, but I’m guessing since they now manage to comply with regulation they just use as little as possible? If they can further limit emissions by using more, then there’s some headroom for improving too.

The problem wasn't just that it was an inconvenience. Under the EPA rules of the time, urea refills were considered critical emission-related maintenance. Initially, this meant that they had to last 100,000-150,000 miles unless the EPA gave a waiver allowing more frequent servicing intervals.[1] This wasn't physically feasible. A couple of years into Dieselgate, they decided they'd allow DEF refills at the oil change interval, which still required much larger tanks than the European models (typically replacing the spare tyre) or cheating.[2] It wasn't until mid-2014 that they decided users could be allowed to refill their own urea tanks and lowered the minimum DEF refill interval for cars to a slightly more reasonable 4,000 miles.[3]

[1] https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=16677&...

[2] https://www.govinfo.gov/content/pkg/FR-2009-11-09/pdf/E9-269...

[3] https://www.govinfo.gov/content/pkg/FR-2014-08-08/pdf/2014-1...

There were some pretty big licensing hurdles to getting the EPA to accept urea tanks as part of an emissions control system: https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=16677&...

Also, note that the 2007 Tier 2 NOx emissions standards mentioned in that document are pretty much as strict as the 2014 Euro6 standard, at least for manufacturers which mainly produce diesel cars. The EU emissions standards were much weaker back then, giving manufacturers more time to develop tech to meet the stricter standard.

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