[allajunaki]

Price difference between petrol cars and diesels are more than simple opportunistic cost and tax.
Diesel, in-spite of all the progress made, still do not match up to the refinements of petrol car of the same segment. Manufacturers add tons of insulating material to cover up the NVH of Diesels, which again drive up the cost.
Diesel engines are heavier owing to the need of tougher construction, which requires stiffer suspension and toughened parts.
Diesel electronics (Modern TDI/CRDI/MJD) are complex and expensive. Even the ECU of modern diesels need to compute a bit more than petrol counterparts, if I'm not wrong. (Note, this does not necessarily mean that Diesels are superior, they need a lot of tech just to remain competitive)
Need to for heavy duty transmission and clutch owing to the torque higher torque engines.
So, needless to say, production cost of the car is much higher.

@Mohit , @spike_arrestor
I think modern diesels combustion is a bit more complex than that. Pizeo injectors now does a control spray of diesel, as much as 5 times per power stroke. So, even though the burn is (near)spontaneous, it is now more evenly spread out by controlled sprays to reduce the vibrations, smooth out the power delivery and ensuring a cleaner burn.

I think, at the end of the day, diesels still are a long way off from providing petrol like sharp response and revs (Most of the new diesels are redlined at 5k, I assume its a limitation of electronics, or electro-mechanical parts, rather than the engine itself).

[kiku007]

Perhaps this could reflect the overall economic scenario.

Why pay a premium upfront to get a diesel car, drive a lot and end up piling up more miles/year which = more $/year?

Instead, buy a petrol car, save on the initial premium/loan EMI, drive less (At the rate at which the petrol prices are increasing, it surely is creating a mental block when I touch the car key) and save money in the longer run.

[extreme_torque]

In these calculations we always tend to forget the fact that the resale value of an old diesel car is atleast 1.5 times the resale value of the equivalent petrol. It is especially true for car which cost above 10 lakhs.

[i74js]

I beg to differ with opinion around excessive carbon footprint of diesel motors compared to petrol.

The carbon footprint is simple CO2 volume in the exhaust and not other gases and soot (which certainly are there but cannot be classified as Greenhouse Gases / CO2). Diesel has higher calorific value per litre of fuel and thus the CO2 emission is in proportion of it as it covers longer distance per litre of fuel consumed. Thus CO2 emission per km of distance is euqal / marginally lower for diesel (compared to petrol) and not higher. I am sure the cost of servicing of diesel innova is same as that of petrol.

Other points of discussions:

- I am not too sure on the higher maintance part as I do not own diesel and petrol counterparts of same car. There is a Innova in our family which has covered 3.8 Lac km (was purchased in the first week of its launch, as Qualis was not available off the shelf - was being phased out). No maintainance so far barring regular service, 7 sets (4 in each set) of tyres, 2 sets of front suspension and 1 set of rear suspension, floor mats, and regular change of brake pads (as recommanded in manual). The timing belt / chain (I am not aware what is being used in the car) has not been touched till date, though the service center checked it thrice for condition. Out of this list, I can only place doubt on front suspensions (because of higher weight of diesel motor). Really not sure why this has been cited as issue everytime in all discussions.

- A diesel car owner (atleaset now) is sure of the kind of increase of fuel cost @ Rs 0.50 / Month while the petrol car owner stays in dark through the life. Otherwise also diesel with dual adavantage of lower fuel cost per litre and higher milage is going to a play an important role in buying decisions.

- Diesel motors are more absure freindly including adultration of fuel, while petrol motors are sensitive.

- The price differential is also not too much for this side of million (its between 50 k to 100 k)

Cheers

[StarScream]

Originally Posted by i74js

I beg to differ with opinion around excessive carbon footprint of diesel motors compared to petrol.

The carbon footprint is simple CO2 volume in the exhaust and not other gases and soot (which certainly are there but cannot be classified as Greenhouse Gases / CO2). Diesel has higher calorific value per litre of fuel and thus the CO2 emission is in proportion of it as it covers longer distance per litre of fuel consumed. Thus CO2 emission per km of distance is euqal / marginally lower for diesel (compared to petrol) and not higher. I am sure the cost of servicing of diesel innova is same as that of petrol.

You're right about diesel having greater carbon density than petrol and hence being more fuel efficient. However, there is another side to it. If you calculate CO2 emissions by liter and not kilometer, then diesel emits more than petrol. Diesel also takes more crude oil to produce. The particulate matter it emits ruins local air quality.

Europe, which focused only on CO2 emissions and hence promoted "clean diesels," is beginning to realize the downsides when it comes to city air pollution. The strictest emission standards are in Japan and California and very few diesel cars are eligible to be sold in those markets.

In India, we are a few generations behind the strictest emission norms. Bharat Stage 4 (Euro 4) actually permits diesel cars to pollute more than petrol cars. Euro 5 is better but we are a long way off from that because it requires a major change in fuel quality to ultra-low-sulfur diesel. Refiners will ideally only make that investment when they make profits from retail sales.

If you look at the progression standards of the Euro pollution limits, diesel will need the most work as you go through Euro 5 and 6, while petrol needs few changes. In other words, Euro 4 is relatively quite advanced as far as petrol is concerned. If you care about carbon footprint, petrol, CNG or hybrid is the way to go.

The differing opinions about diesels explains why the Japanese are so keen on hybrids.

[i74js]

Originally Posted by StarScream

You're right about diesel having greater carbon density than petrol and hence being more fuel efficient. However, there is another side to it. If you calculate CO2 emissions by liter and not kilometer, then diesel emits more than petrol. Diesel also takes more crude oil to produce. The particulate matter it emits ruins local air quality.

You have answered it yourself. The carbon footprint is CO2 emission per km of run and not per litre of fuel consumed.

Diesel has a lower CO2 exhaust as I stated in my post. I have specifically talked about other emissions but they are not classified as GHGs or carbon footprint, thus from the carbon footprint point of view, diesel is lower than petrol (CNG has the lowest though).

Cheers

[StarScream]

Originally Posted by i74js

You have answered it yourself. The carbon footprint is CO2 emission per km of run and not per litre of fuel consumed.

Diesel has a lower CO2 exhaust as I stated in my post. I have specifically talked about other emissions but they are not classified as GHGs or carbon footprint, thus from the carbon footprint point of view, diesel is lower than petrol (CNG has the lowest though).

Cheers

I don't think there is an accepted definition for carbon footprint of cars. Per km hides the fact that diesel actually contains more carbon per unit of volume and hence emits more CO2 than petrol by the same measure. Using the per km emission "definition" is misleading, was my point. Also misleading is just considering tail pipe emissions and not those of production and transport.

Considering that diesel is cheaper in India plus the cars that use it more efficient, one will end up driving them more and hence use up more fuel during the life cycle of the car, which negates any mileage and hence emissions advantages. Your argument holds good if a diesel and petrol car are driven for the exact same kms over their life, not otherwise. In fact, the deadliest greenhouse gas is methane, the key component of CNG. At the tail pipe it's the cleanest by about 50% but if you consider production and pumping leakages, CNG ends up being only about 15% better than gasoline.

Also diesel soot is considered a greenhouse gas:
http://www.theguardian.com/environme...global-warming
and as per my previous post, our diesel cars pump out more of the stuff because we don't have ULSD or particulate matter filters as they aren't mandated by our emissions standards.

[acroback]

I have a Duster which runs on Diesel and a Santro running on petrol.
I drive Duster while wife drives Santro.

My next vehicle which will hopefully replace Santro, ought to be a turbocharged petrol. Diesels are good and economical which make sense for my 24K annual running.

A small well sorted turbocharged petrol is what I will look into. Hopefully Tjet will be fixed for its niggles and poor ergonomics by then.

[slamnos]

Unlike other developed nations, in India diesel vehicles are selling with a premium, even with such a premium it made sense as the price between petrol & diesel were huge, now that this gap is narrowing down, this was sure to happen.

[sandeepmohan]

Originally Posted by acroback

Hopefully Tjet will be fixed for its niggles and poor ergonomics by then.

There are no known niggles for the T Jet.

Poor ergonomics yes but I'd limit it down to the driving position. Once again, it is not bad to the extent that you can't drive the car. Its just different. I really doubt if Fiat will be addressing this on the upcoming Linea.

[SKavuri]

Originally Posted by SPIKE ARRESTOR

Thanks Mohit for the explanation, power

Not really I think. Have you noticed the noise behavior of an IDI and a DI engine?

Spike

One main difference between CI and SI engines is that CI engines have higher compression ratio.
This leads to:
- Heavier engine, as the engine needs to be stronger (thicker and hence heavier) to contain the higher pressure
- Higher noise due to higher compression ratio

[SPIKE ARRESTOR]

Mohit, Skavuri, I guess we are going offtopic here. This thread is better suited for our discussion.

http://www.team-bhp.com/forum/techni...l-engines.html

Spike

[sandeepmohan]

With the current rates for petrol, I see the trend moving back to diesel. It makes no sense now. Even if you do not run your car enough to justify a diesel, it is still better to buy a diesel. With a difference of about Rs. 26 between fuels, you are still going to save plenty to factor in the additional cost when it comes to maintenance. The nature of a diesel engine is such that you don't burn far too much gas even in bumper to bumper traffic. This is quite the opposite with a petrol. A really bad situation for petrol car owners.

[gopa99]

Originally Posted by RSR

Here is an interesting trend for those who are interested.

The diesel-petrol sales split for 2013 so far:

Jan - 41845 : 10185 ~ 4 : 1

Feb - 13466 : 3900 ~ 3.5 : 1

Mar - 38714 : 8212 ~ 4.5 : 1

Thanks, one doubt, is this data considering all vehicles under passenger car category? i.e hatchs, sedans, suv's and pickups all included?

Originally Posted by SKavuri

One main difference between CI and SI engines is that CI engines have higher compression ratio.
This leads to:
- Heavier engine, as the engine needs to be stronger (thicker and hence heavier) to contain the higher pressure
- Higher noise due to higher compression ratio

With the all aluminum engines, like the first one in the honda amaze, is this assumption still valid?

[RSR]

Originally Posted by gopa99

Thanks, one doubt, is this data considering all vehicles under passenger car category? i.e hatchs, sedans, suv's and pickups all included?

This data is only for cars with both petrol and diesel engine options, whose sales split for the respective month was provided by the manufacturer, irrespective of body style. So if a manufacturer had provided a sales split for that month, it would be included. This list may vary from month to month, and is available in the monthly sales threads posted by GTO and parrys.