[earthian]

After having nearly made up my mind to buy a Mercedes Benz GLE 250 D; there has been questions raised by a friend ( who was also going to buy one) on the desirability of diesel from purely an environment point of view. He was of the view that GLC 300 would be more environment friendly than the GLE 250 D. The GLE 400 is outside our price range and hence we would have to evaluate the GLE 250D with the GLC 300.Questions asked are:

1. What are the differences in emissions between diesel and petrol ( of similar engine capacities)in general and the GLE 250 and the GLC 300 in particular?
2. Whether there is any risk in diesel engines ( for SUVs), beyond a particular capacity, being banned ( for want of a better word) by the authorities? ( as we saw at Delhi recently-though the verdict was overthrown by the SC)

The use of the vehicle would be for self driven trips in India for pleasure. The possible occupants would not exceed 4 and comfort of driver and passengers would be a main decider. Cost of fuel would not be a consideration.
Could you guys advise on the above please?

[cool_dube]

Originally Posted by earthian

After having nearly made up my mind to buy a Mercedes Benz GLE 250 D; there has been questions raised by a friend ( who was also going to buy one) on the desirability of diesel from purely an environment point of view

Excellent thread - I was about to start one.

While there have been numerous debates on the merits/demerits of diesels over petrol and vice versa, diesels are undoubtedly more harmful for the environment than their petrol counterparts of the same 'generation'. Given this, it is hardly surprising that most European countries plan to ban diesel vehicles completely over the next 5-10 years. That said, from a pure enthusiast's perspective, the low-end torque of a diesel engine pulling a 2-ton SUV like a locomotive is nothing short of pure bliss! However, it is high time that good sense prevailed and people start placing the well-being of our planet above their adrenaline rush!

Having driven diesel SUVs and Jeeps for over 15 years now, I am switching over to petrol in phases before moving on to EVs, which is the future of mobility anyways.

[earthian]

Originally Posted by cool_dube

... diesels are undoubtedly more harmful for the environment than their petrol counterparts of the same 'generation'. .

Not so fast, cool_dude. There is a big debate on this and the jury is still out. In very simple terms, a diesel engine is more efficient than a petrol one and produces lower CO2 emissions, but higher particulate matter. While one impacts the world at large ( by global warming) the other impacts the health of the city dweller.
Some good reading can be had here and here.

Edit: So from a planet perspective, the diesel is the preferred choice and it was due to the global warming scene that Europe went whole hog into diesel. But in India we are grappling with local pollution issues, mainly being smog, where SPM (suspended particulate matter) plays a big role.

Hence my question.

[deerhunter]

Originally Posted by earthian

Not so fast. There is a big debate on this and the jury is still out. In very simple terms, a diesel engine is more efficient than a petrol one and produces lower CO2 emissions.

A new study has shown that diesel maybe emitting more carbon than previously thought. So not only from the health perspective, but also from the perspective of global warming, diesel may be more dangerous.

https://www.theguardian.com/environm...-report-claims

On this analysis, some 20m cars in use since the 1990s may each have produced 40-80g of CO2 equivalent per kilometre more than previously thought.

The autolobby has dismissed the study.

But the car industry says that diesel cars still emit 15% less carbon dioxide per kilometre than their petrol equivalents.

Another link about the same:
http://www.bbc.com/news/business-33254803

We are now learning that millions of motorists who've bought diesel cars believing they were less harmful to the environment have been equally misguided. Diesel cars emit less carbon dioxide (CO2) than their petrol equivalent, we were told. In fact, not only are CO2 emissions almost identical on average, but they also produce large quantities of noxious pollutants linked with thousands of premature deaths.

[Ruchitya]

If my memory serves my right, diesels have higher calorific value and lower specific heat than petrol. So per litre, they are more efficient. Fuel efficiency figures for diesels are almost always when hauling the same vehicle body. However, I think as earthian mentioned, smog, which is due to NOx and unburnt hydrocarbons is a bigger problem with diesels. Yet to read up on figures for the same. It would be better to read about the amount of CO2 and other emissions for each of the engines, and multiply that by the estimated running per year. See if it makes a significant difference, switching to the other engine.
My humble opinion is if the engine can clear Euro 6, which should be implemented in India from 2020, you are probably covered from an environmental perspective. Also, there will probably be a much bigger difference in your environmental impact, atleast locally, if you consider hybrids.
There are alot more areas to improve our carbon footprint apart from the cars we drive too.

[Turbanator]

Well, the new Lexus RX-450h would have been no-brainer had Toyota gone the way Germans operate here and priced it around X5 / GLE which is the segment it competes elsewhere. Now the only options with you will be to look at CO2 and other ratings, BMW India has some very clear data but for others, you might have to dig little deeper.

The possible occupants would not exceed 4

You can also look at GLE 450 AMG Coupe. Up here in North there were some rebates and these are CBU models. It sounds Ok and can be an option to GLE which is common but practical.

The use of the vehicle would be for self-driven trips in India for pleasure

If you intend to use this only for few months when you are in India, see if you can buy something jointly with your friend and pick VOLVO XC90- T8.

But for all practical purpose, I think nothing beats X5 - pick the M variant they are having good discounts- 8-9 Lac Ex-showroom if I recollect ( don't expect 15 Lac though ! )

[earthian]

Originally Posted by deerhunter

A new study has shown that diesel maybe emitting more carbon than previously thought.

The autolobby has dismissed the study.

Yes, i read that article and as mentioned, it is not conclusive.

Originally Posted by Ruchitya

If my memory serves my right, diesels have higher calorific value and lower specific heat than petrol. So per litre, they are more efficient.

Nothing wrong with your memory. Here is a quote from the article in the Guardian, mentioned by deer hunter :

“Diesel fuel has a higher energy content per litre than other fuels,” said a spokesperson for the European Automobile Association. “Moreover, diesel engines convert more of this energy into useful work. Due to these two factors, diesel cars consume about 20-25% less fuel by volume than equivalent petrol cars.”

“A diesel engine with a filter removes 99.99% of black carbon emissions and today all the diesel cars have filters, so there are virtually no black carbon emissions anymore,” he said. “We can see the filters are working because the concentrations of black carbon are going down year by year.”

Originally Posted by Turbanator

... will be to look at CO2 and other ratings, BMW India has some very clear data but for others, you might have to dig little deeper.

Yes, am trying to dig out emission data for the GLE 250 D.

But for all practical purpose, I think nothing beats X5 -..

OT , but curious to know that apart from the inline 6 cylinder peppy engine, what else has it in comparison with the GLE 250 D? Maybe better media management software? And BTW, i stay in India and am busy being a full time Vella.

[Turbanator]

but curious to know that apart from the inline 6 cylinder peppy engine

I won't have an answer to that, Sir . All the best with your hunt.

[vivee90]

The word "Efficient" and "Eco-friendly" are very contextual.

In my opinion, the environmental friendliness cannot be attributed to either Petrol or Diesel.The decision depends on the application and the technology in the car. On a general note, Diesel combustion produces a lot more harmful emissions that are controlled in complex after treatment and I should say the bandwidth for that control is still very narrow (and even mysterious, like VW showed us). Like with VW debacle, the time that the after treatment systems are active is very limited in everyday conditions.

Petrol on the other hand is much more straight forward in emissions. The majority of it are CO2 and are directly proportional to the amount of fuel the car consumes. So, a petrol engine pushed to a limit is quite polluting while inside their comfort zone, they are pretty straight forward in pollution.

While a Petrol engine is efficient for soft cruises and city driving in small cars, Diesel is more efficient for high torque applications like freight carrying and big cars.

In your case, if you are not going to drive a lot on mountains or off-road or use the car to pull a trailer (which is the case in EU) a Petrol is more efficient environmentally. As for the excess CO2 emission, you can offset by growing a few trees(funny yet logical).

And the environment aspect extends much further than tail pipe emissions. I could not find the localisation figure for GLC and GLE but assume both are assembled in India. The probability that GLE is shipped all the way from US as CKD is high than GLC which could use few components locally made. You can clarify this information and decide which causes more environmental damage even before a drop of fuel is added. Another aspect is the weight, GLE is definitely heavier and means a lot more damage went into this than GLC. So, you can also evaluate that aspect in your decision.

Looking forward to your final choice and fellow bhpians comments. Nevertheless, wishing you a great experience with these beautiful beasts.

[deerhunter]

While the global warming potential of CO2 is well discussed in the forum, the same about NOx is not discussed much. Diesel produces a lot of NOx, compared to petrol combustion, of which N2O is a greenhouse gas and other NOs promote the formation of tropospheric ozone, which is a greenhouse gas.

So while comparing, the greenhouse potential of NOx has to be taken into consideration.

[earthian]

Originally Posted by Ruchitya

My humble opinion is if the engine can clear Euro 6, which should be implemented in India from 2020, you are probably covered from an environmental perspective....

That would be a safe bet. While it is quite frustrating to dig out emission figures of the GLE 250; one aspect that i need clarity is whether the car is BS VI ready or not? The fuel quality for BS VI is a major issue, but apart from that does the car come equipped with the diesel filters required by BS VI?

There are alot more areas to improve our carbon footprint apart from the cars we drive too.

Well said.

Originally Posted by vivee90

And the environment aspect extends much further than tail pipe emissions.

Again, well said. But the total eco friendliness of the machine has neither been understood, nor calculated. We are still coming to terms with the importance of environment protection and it could quite some time, before we not only understand this, but more importantly accept it. Majority of us are probably still lower down in the Maslow's hierarchy of needs.

Originally Posted by deerhunter

While the global warming potential of CO2 is well discussed in the forum, the same about NOx is not discussed much. Diesel produces a lot of NOx, compared to petrol combustion, of which N2O is a greenhouse gas and other NOs promote the formation of tropospheric ozone, which is a greenhouse gas.

So while comparing, the greenhouse potential of NOx has to be taken into consideration.

Good point, but as informed quite difficult to get hold of figures.

[Hayek]

Am sorry to be a dampener but SUVs by definition are NOT eco friendly, when used in normal urban applications. A car would be a lot eco friendlier. Agree with those who say that hybrids are better than diesels esp in urban applications. For highway cruising, in my view diesels are fine - as emissions are in locations where they don't materially affect the local environment.

Have always been a petrol engine guy but am picking up an X3 20d now as I am frustrated by the terrible resale on petrols

[cool_dube]

Originally Posted by Hayek

Am sorry to be a dampener but SUVs by definition are NOT eco friendly, when used in normal urban applications

Completely agree! Heavier the vehicle (read SUV), more the fuel consumption for same distance covered and consequently, more the emissions and damage to the environment, irrespective of the fuel used.

[earthian]

Originally Posted by Hayek

Am sorry to be a dampener but SUVs by definition are NOT eco friendly,...

Originally Posted by cool_dube

Completely agree! Heavier the vehicle (read SUV), more the fuel consumption for same distance covered and consequently, more the emissions and damage to the environment, irrespective of the fuel used.

No doubt.
The factors which would influence decision are:

1. Safety.
2. Ride comfort.
3. Reliability.
4. Mental comfort.
5. VFM ( comparitively with other equivalent).
6. Environment compliant ( with present and immediate future norms).

I have no doubt that an SUV is less environment friendly, then say a small car witha 800 cc engine.
But, i need an SUV. Maybe 'want' is a better word than 'need'.

[Skyline_GT]

Not much of a greenhead myself and I firmly believe in being financial and budget friendly over being ecofriendly. I would vote for Diesel!
Diesel engines nowdays a more much more efficient and clean compared to how they were a decade ago. Diesel is as of today still light on the pocket compared to Petrol.
Another important factor we need to consider is the engine size, since all the SUV's are powered by massive powered engines the amount of petrol burned would be far more inefficient (financially) as compared to the diesel.