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Mazda6 diesel sedan offers up to 60 mpg US

Mazda6 Sedan & Wagon (European Specification). Click to enlarge.

Both the wagon and sedan versions of the new Mazda6 made their collective debut at the Paris Motor Show. The Mazda6— now in its third generation— is also the company’s first mass-production model equipped with i-ELOOP, its brake energy regeneration system.

i-ELOOP joins the i-stop idle-stop system and SKYACTIV powertrains, chassis and body (introduced on the CX-5) to deliver fuel consumption as low as 3.9 l/100 km (60 mpg US) and CO2 emissions of 104 g/km (European combined cycle with standard diesel SKYACTIV-D 2.2 and SKYACTIV-MT six-speed manual), in the CD-segment without sacrificing performance.

Mazda is offering the choice of five SKYACTIV engines (two diesels and three gasoline powerplants) coupled with six-speed manual or automatic transmissions in the Mazda6. Most are available with i-ELOOP as well as i-stop.

i-ELOOP (short for “intelligent Energy Loop”) uses a supercapacitor to store electricity recovered during deceleration to power the vehicle’s electrical systems, thereby improving fuel economy.

Mazda’s engineers determined that a typical vehicle deceleration phase lasts only about 10 seconds. Realizing that the effectiveness of regenerative braking to date has been limited by the charging and storage drawbacks of conventional lead-acid starter batteries, they instead adopted an electric double-layer capacitor (EDLC), which recharges fully within only a few seconds. An efficient 12V-25V variable voltage alternator generates the electricity and charges the EDLC; a DC/DC converter then steps down the voltage to power electrical components like the climate control and audio systems, with any surplus going to the starter battery.

A full capacitor charge is enough to run the vehicle’s electrical systems for a minute or so. This makes i-ELOOP an ideal companion for i-stop, as there is no need to revert to battery power even when Mazda’s idle-stop system has shut the car off. During stop-and-go city driving, charging often resumes before the capacitor is fully discharged. i-ELOOP can therefore produce most if not all of a vehicle’s electricity needs, whereas normally some of the engine’s output is required just to drive the alternator. By freeing up this engine capacity, i-ELOOP increases fuel economy under everyday urban driving conditions.

Mazda6 Engines
  Gasoline Diesel
Standard Power
High Power
Standard Power
High Power
Displacement (cm3) 1,998 2,488 2,191 2,191
Valves 16
Camshaft drive Timing chain
Fuel injection system Direct injection
Compression ratio 14.0:1 13.0:1 14.0:1
Max power (kW) 107 @ 6,000 121 @ 6,000 141 @ 5,700 110 @ 4,500 129 @ 4,500
Max torque (N·m) 210 @ 4,000 256 @ 3,250 380 @ 2,000 420 @ 2,000
Powertrain FWD
Transmissions SKYACTIV-DRIVE (AT)

The gasoline engined models achieve Euro 5 emissions standards, while the diesel models are Euro 6 compliant.

The SKYACTIV-Body on the Mazda6 is lighter yet stronger than the current model through the use of more ultra-high tensile steel and other innovations to bolster the body’s structures.



This is very good for a car of this size.
Clever to save the braking energy into a capacitor, without a hybrid system.


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.


Why do you believe the rediculous NEDC mileage claims? NEDC is way over inflated as a fuel economy yardstick.

Euro socialist greens don't give a damn about toxic emissions, or fuel economy. All they worry about is CO2 emissions because they can T-A-X them.


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.


In comparison, the BMW 320d EDE gives 4.1 l/100 km and 109 g/km. I have been very skeptical about the new Mazda engine but I will now give them all the credit they deserve. Good job Mazda!


@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.



The EU has started to regulate PN emissions from diesel vehicles (phase-in started September 2011 - Based on footnote c., it appears all diesel models will have to meet that standard by January 2013. Also note that DI petrol vehicles will have a PN standard starting in September 2014, but they're given an order-of-magnitude leeway for the first three years compared to what diesels have to meet now.

As for PN emissions from Prius, I haven't seen any data, but PM (mass) measurements made on a Generation 1 Prius showed emissions of 0.004 g/km in the FTP test duty cycle (L. Graham, "Chemical Characterization of Emissions From Advanced Technology Light-Duty Vehicles." Atmospheric Environment, 39 (2005), 2385-2398, Table 4 - page 2390). That would equate to about 0.006 g/mile, which meets the U.S. 0.01 g/mile Tier 2 standard, but is higher than PM emissions from any of the LD diesel vehicles currently certified in the U.S. as far as I know.

Hope Peter XX doesn't mind me answering a question directed to him.


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.


Mazda 6 (diesel + regenerative breaking with ultracapacitors as storage medium) is a forerunner of diesel-hybrid cars to come.

With hybrid technology, the diesel engine can be further downsized from 2L to something smaller and still more efficient, since the electric motor will handle the (infrequent) needs for high peak power output.

The net effect will be 70+ mpg, as has already been demonstrated by Peugot, VW and others.

The g(CO2)/mile of a 70mpg diesel-hybrid is 28-30% lower than than that of a Nissan Leaf electric car running on US average grid mix, as measured in g(CO2)/kWh.

Diesel-electric hybrids is THE way to go.


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.


thanks for the reference about 1st Gen Prius PM. However, the PM number published there seem to be flawed. Here is a full paragraph quote from the article (p. 2389):

"The composite criteria emissions and fuel economy for these vehicles as obtained over the FTP test are summarized in Table 4, along with a number of different light-duty emission standards applicable to vehicles sold in Canada. For the PM emissions, small leaks in the transfer line delivering the raw exhaust to the dilution system resulted in higher than expected gravimetrically determined PM emission rates for the low-emitting gasoline-fuelled vehicles. Also reported in Table 4 are total carbon (TC) emission rates as determined by a thermal optical transmission method that may be used as a surrogate for the true PM emission rates for these vehicles. The leaking transfer line, while under a slight vacuum during testing, allowed unfiltered laboratory air into the system, resulting in PM contamination that is thought to consist mostly of concrete dust from the test cell floor."



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.,, 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 (


Modern diesel engines do not have to be much heavier than the gasoline counterparts. My rule of thumb should say roughly 15 kg, i.e. 5 kg for the cylinder head (including fuel injection components) and 10 kg for engine block and accessories (including a slightly larger battery) for the same cylinder capacity and turbocharging in both cases. This gives somewhat higher torque in the diesel case and higher power in the gasoline case but about similar drivability in both cases. It is also possible to find other basis for comparison but in general, weight is not an issue for using diesel engines with hybridization and plug-in capability. The weight of batteries is the real show-stopper but that also applies to gasoline engines.


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.



>>Diesel Plug-in hybrid is NOT the way to go.

I was advocating a Diesel-Hybrid, not a plugin. I think that ought to be clear from the context.

I have spoken about this at length in other threads (search Jus7tme hybrid), but just for the record:

A plugin-hybrid is the worst of both words. It produces more CO2/kwH than a plain because the electrical grid-mix contains too many coal-fired electricity. And on top of that it is even worse than an electric car, because of the added weight from the regular engine, be it gas or diesel.

Upshot: Hybrid cars are good, Electric cars are bad, Plug-in hybrios are EVEN WORSE.



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.


CORRECTION: The above post is NOT, repeat NOT, in response to Carl in particular.

It is a response to the general idea that particle emissions is a figure of merit that we should emphasize instead of or above pure energy efficiency or CO2 efficiency. I think doing so is a bad mistake. Particle emission problems is well under control for engines.

For coal plants, we should be concerned.


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