Yes, it seems that Mazda in one of the few manufacturers who started to think smart & active and applied the right technology to capture more braking energy with more efficient ICEs.

All others could do likewise and boost fuel economy to 60+ mpg on all average mid-size cars.

Why wasn't that done across the board a few years ago?

Gas-fuel price has been high enough in EU for 20+ YEARS.

@D
My advice to you is to do some research before posting the comments you did. EU regulates emission or nanoparticles (limit on particle number); the most harmful emission component that we know of. Thus, particle emissions after the DPF are at – or below – the level in clean ambient air and also lower than most gasoline cars. US EPA does not even bother to regulate nanoparticles.

Many EU member states do have economic incentives for both emissions and fuel consumption (CO2). What does the USA have? Nothing! Consequently, the average fuel consumption for new cars is far lower in the EU than in the USA.

Who said that the US FTP test cycle is better than NEDC? US EPA should promote the worldwide harmonized driving cycle, instead of opposing it, so we could end this discussion and start to compare apples with apples.

@Peter XX
Does EU regulate the particle numbers yet? I have not seen any PN data on any model sold so far.
Any idea how the PN of a small diesel compares to PN of a Prius? I have the feeling the Prius is still much cleaner due to its lower compression ratio and port fuel injection.

Thanks Carl! I do not mind. I will contribute with some complementary information.

My diesel car has certified PM emissions of 0.000 g/km. Generally, PM is <0.001 g/km for diesel cars with DPF, unless the background air level in the measurements has been high or there is a carry-over in the measurement system from a previously tested (dirtier) car. Since DPFs were introduced a couple of years ago, diesel cars have achieved these levels since long, albeit that some older certification data indicate a somewhat higher level due to the measurement artifacts I indicated. Since PM level is so ridiculously low from a DPF car, particle number (PN) is a much better metric to regulate particulate emissions. Instrumentation for measuring PN is simply more accurate. In addition, most of the matter collected as PM is actually not solid particles but adsorbed volatiles from the gas phase. This is because the sample filter used in PM measurement simply adsorbs such stuff. This, so-called filter artifact, is not small. Volatiles comprise more than 95% of the mass. Thus, the measurement error is >95% and the “real” solid PM level would be at least a factor of 20 lower than what we actually measure. These volatiles can be evaporated by heating the sample filter. However, if this is done, a microbalance will not be able to detect any particle mass at all. This “real” level is also far lower than the PM in ambient air, so the DPF actually cleans city air.

As mentioned, PN is a better metric than PM and, in fact, the PM limit is “redundant”. A DPF designed to meet the PN limit will give PM emissions one order of magnitude lower than the PM limit. While US EPA has also realized what I have mentioned above and has also carried out several studies on the topic, they still do not consider regulating PN. Thanks to the European car manufacturers, the same DPF technology is anyhow used on cars marketed in the USA. Environmentally conscious people in the USA should thank EU for this development rather than scorn the EU authorities on false ground.

In addition to the mentioned favorable development, EU has also taken measures to drastically reduce fuel consumption and CO. While some people on this site seem to think that this reduction has been easy, my opinion is the opposite. I also would like to point out that further reductions will become increasingly difficult.

@Jus7tme
Diesel Plug-in hybrid is NOT the way to go.
Non-plug-in Diesel hybrid may be.
Diesel Plug-in hybrid simply amplifies disadvantages of diesel: Higher weight and higher price than gasoline models.
Usually people either drive a lot in the city, or inter cities. Those who spend most time in city driving should buy cheaper (and lighter) gasoline plug-in model.
Those who drive mostly outside cities, should buy a diesel or hybridized diesels, with a very small battery, not to carry all the time heavy battery, which is just a dead weight on long trips.

@DFGeneer,

Thanks...I didn't notice the apparent error in the measurements in that paper. I did not question the results because other sources have qualitatively mentioned "soot" emissions from Prius' exhaust (see, e.g., http://www.nrel.gov/vehiclesandfuels/nfti/pdfs/workshop_obj_lawson.pdf, slide #7). So, I'm not aware of any reliable data on the PM/PN emissions of Prius.

Nevertheless, as Peter XX has mentioned, PN emissions from DPF-equipped diesel engines are at or less than ambient. That would make it virtually impossible for a Prius or any other gasoline engine to emit less PN than current diesel technology (i.e., with DPF).

The California Air Resources Board (CARB) tested a European diesel car with DPF and found that "After the first 300 seconds of the NEDC cycle...particles measured from multiple particle counting systems are close to tunnel background..." (CALIFORNIA’S INFORMAL PARTICIPATION IN THE PARTICLE MEASUREMENT PROGRAMME (PMP) LIGHT DUTY INTER-LABORATORY CORRELATION EXERCISE (ILCE_LD), FINAL RESEARCH REPORT, October 2008). Since CARB is typically not a supporter of diesel technology, it's unlikely that it would error in favor of diesel.

Another European study shows that PN emissions from the exhaust of a diesel car with DPF are lower than that of filtered dilution tunnel air (http://www.dieselnet.com/papers/0209czerwinski/).

After further review, it does appear a few studies have looked at PN emissions from gasoline-hybrid vehicles (e.g., Robinson, Mitchell K.; Holmen, Britt A., "On-Board, Real World Second-by-Second Particle Number Emissions from a 2010 Hybrid and Comparable Conventional Vehicle.")

This study referenced an earlier study (Christianson et al.) which found that PN emissions of four hybrid vehicles (including a Generation II Prius) were similar to conventional gasoline vehicles, including increases during acceleration, transient operation and increasing vehicle speed. This study showed that the hybrid version of the Toyota Camry demonstrated PN emissions in a real-world city driving test two time higher than the conventional version despite the hybrid versions ICE shut down 16% to 57% of the test duration, due to high restart PN emission rates according to the study.

According to another study (Bosteels, et al., "'Regulated’ and ‘Non-regulated’ Emissions from Modern European Passenger Cars." SAE International 2006-01-1516), PN for a conventional gasoline vehicle (MPFI) ranged from 1.2X10^11 to 4.6X10^11 particles/km over several different test duty cycles, while a diesel vehicle with DPF had PN emissions over the same duty cycles ranging from 1X10^9 to 9.9X10^9 particles/km. (Another study (Karlsson) showed PN emissions during DPF regeneration at 1.39X10^11 particles/km).

Thus if hybrids' PN emissions are similar to, or up to two times higher than, conventional MPFI gasoline vehicles, it follows that hybrids would have PN emissions about two orders-of-magnitude higher than diesel with DPF.

Carl,

You are causing confusion by worrying about particle emissions, claiming that Prius is bad. This is a Red Herring at multiple levels.

If you are going to worry about particle emissions, you should be looking at the coal-fired power plants that feed the electrical grid. and thereby feed into electric cars.

http://www.greenpeace.org/international/en/campaigns/climate-change/coal/Coal-Power-Plants/