[supertinu]

I am not a technical expert but believe it has to do with the generation of injectors and CRDi technology that makes a difference. If you recall the first gen of CRDi 3 cylinder on Hyundai Accent which very popular but also very tractor like sounding at idle. Later Ford brought the 2nd gen of 1.4TDCi motor which was lot better but again very clattery by today's generation. From 3rd gen onwards with newers engines on Hyundai verna etc they got really better and smoother at idle.

I have a XUV500 which has a butter smooth engine at idle vs. Ford Figo 1.4 TDCi which makes such a racket at idle.

[Arjun Bharadwaj]

Our i20 has done ~2,58,000 kms. The engine still sounds reasonably silent and on the move its smooth! When I compare that to Ventos that have done less than 50k, they sound agricultural in comparison.

Apart from the power delivery, good VW/Skoda got rid of the diesels.

[Joshua_Ray]

A very interesting thread, in my opinion only the PD engines (both 1.9 and 2.0) are extremely loud and noisy during cold starts. After a minute of idling, they settle down to a bearable level.
The noise is probably due to the purely mechanical operation of the pumps (pumpe düse) feeding fuel to the injectors.
The 2.0 CR's are more refined in this area, though still quite loud when compared to Hyundai diesels.
On the positive side, the cabin insulation allows very little NVH inside the cabin, so the racket outside seldom bothers the occupants (apart from some stares and glares from bikers, wondering why a posh car makes such a cacophony)
Another negative is, you cannot sneak out for a midnight drive, without waking up everybody in the house

[tanaysn]

Interesting article and agreed the VAG 1.5/1.6TDI motors are louder than the 2.0 TDI. The 1.5 sounds a lot louder on the outside but inside the cabin with the windows rolled up, they are okay IMO.

On the comparison note, the Maruti DDis 125 2 pot motor used in Celerio was a disaster and could give some complex to few tractor engines too.
The 1.5 Maruti diesel engine (early 90s I reckon) used in the Zen and the Esteem were loud too .

[adv.yzr]

Greetings,

I think the 4-cylinder version diesel engine sounded much better than the 3-cylinder. The one with 3-cylinder surely sounded pathetic and contributed to the popular notion that diesels are way too noisy. This changed post launch of 4-cylinder engine. Though, I agree Honda City diesel was equally noisier as compared to Polo, Fabia or car with same engine (3-cyl). Things have improved many notches above in contemporary times.

Thanks.

[prabhu.reddy92]

My brother owns a 2015 VW Polo Highline Diesel and I love the way the engine sounds. Yes it is noisy but I love the sound to the core.

And I own a 2019 Elite i20 Asta (O), where no one can make it out if it's running a diesel or petrol engine. To make things worse there is no mention of CRDI or VTVT or whatever to tell if it's a diesel or petrol😂, and yes i miss the sound of the Polo when i am driving around in i20.

[Zinda]

That's true - Vento/Rapid are very noisy, specially on low rpms. I am talking about the noise outside, and not from the cabin NVH perspective. It is very coarse diesel clutter during idling. iDtech too isnt a refined unit either. These units, when idling, aren't very different to Ambassador Diesel.

I would rate my XUV500 somewhere in middle - its bit noisy during idling, but sort of well insulated from inside. And then this diesel is relatively rev happy so compensates well with Torque and grunt.

Only one Diesel which has pleasantly surprised me with its NVH (both inside and outside too) in <20 L segment is Creta 1.6 CRDi! I literally had to reconfirm the CRDi badging on tailgate

[Gosha]

I have a 2011 Vento 1.6tdi while my friends have a 2013 Vento 1.6tdi and a 2016 1.5tdi. I found my 1.6tdi to be a bit loud on cold starts and once the engine warms up the sound reduces. I personally feel that it sounds rather sporty on revving. Compared to my 1.6 tdi, the 1.5 tdi had more clatter. Both my friends had to update the diesalgate software since their car's were in waranty. Post the software update the diesel clatter was more prominent with decreased power compared to before. I had changed 3 of my injectors post which engine seemed more quiet and then with a remap the car was sounding smooth as compared to before.

[VeluM]

My father's Vento 1.6L diesel is quite noisy, but not distressing like the Innova 2.4, or Honda 1.5. Hyundai diesels are almost unbelievably quiet in comparison to any others.

I don't know why this specific VW diesel is noisy, but it sounds (as far as I can remember) something like the old 1.9PD engine in the original Octavia at idle. The 2.0L and larger capacity diesels are either much quieter or far better damped.

The Vento 1.6 doesn't much noisier at revs, rather tends to smoothen out. It is just the idle that is quite loud (in my experience). At highway speeds one is always aware of the diesel at work, but it isn't intrusive or tiring.

Makes up for it IMHO with the terrific performance and incredible fuel efficiency. My father easily gets an indicated 17kmpl in city (Bangalore) and 23+ on the highway. It has superb highway range, and there has not been any drop in performance with time, nor any smoke under acceleration.

Hyundais are the worst in terms of smoke under acceleration as far as I've seen.

[aniketi]

I own diesel myself so i guess i can comment here. I have Ertiga diesel with Fiat multijet engine, it make noise in the morning on cold start but settles nicely after few minutes once it is warm. On highways, its wonderful. With AC on & music playing, you barely hear any sound inside.

My friend has diesel Vento & its very loud compared to mine. Inside also you can clearly hear the noise even when windows rolled up & AC is on. It's quite loud and annoying to be very honest.

[dicor]

In order of decible produced by Diesel engines, here are my observations

1. 80000 KM driven TATA Indica (Diesel)
2. Aged Toyota Innova / Fortuner. (It just sound like tractor)
3. TATA Safari (that cruel injector sound of Dicor engine)
4. Skoda / VW
5. Honda Diesel (Amaze / City)
6. Aged Ford Fiesta / Ecosport


For silent engines
I've not experienced Kia so no comments

1. Hyundai Diesels (Butter smooth and silent since 2002 Accent CRDi)
2. Renault Diesels (Duster / Verito)
3. Fiat MJD / Maruti DDis

Mahindra's MHawk engines are pretty good in terms of noise insultation.

[Kishen.padiyar]

Did we forget the class topper here? The 1.4TDCi from Ford? As someone mentioned earlier in the thread, EGR could be one of the reasons. The BS3 1.4 TDCi though noisy did not sound annoying compared to the BS4 ones. The difference between the two is that the latter has a more aggressively tuned EGR to keep the NOx emissions in check.

Similarly, since the VAG TDi CRs entered the Indian market in 2010, I guess they were BS4 right from day 1. The earlier PD TDis were a bit more refined (comparatively).

[glovins2004]

I drive 2014 VW VENTO TDI 1.6, the lot without the writing “Volkswagen” on the left side of the boot. I personally like silent cars and Honda city was top of my list during the search for an upgrade in 2014. However, the contemporary German stance and stunning performance overshadowed the NVH preference. I adore this piece of machine from all angles.

I somehow fell the NVH of my car much improved as it aged. I doubt whether any software updates were done during regular service but it’s much better these days and even more better when warmed up, for e.g when I pull over for a break after a long drive, it’s almost like a petrol car unless i keenly observe.

On a lighter note, once a SA told me VW diesels should roar like a lion. Really.

[Torque250]

I have seen some comparisons between city iDTEC and tdi. As I am in possession of both City iDTEC and polo GT TDI in my garage, I think i would be eligible to clear doubts on that front.

Yes the engine noise was loud in city diesel, but the pedals were smooth to operate, with no vibrations transmitted to it. In traffic signals, when the AC compressor kicks in with a roar, some hypervigilant bikers would frantically squeeze their bikes through non available space, as if some volcanic eruption is about to happen.

Coming to the polo, its engine was noticeably louder than the honda city, and the drive train movements can be felt on every pedals out there. I will cringe sometimes while pressing the quivering clutch.

To conclude, If you can mimic the sound of city diesel, do it with closed ears to get the sound of tdi.

[PrasannaDhana]

I have owned some of the noisiest diesels in their respective segments

1. Sumo Gold (3.0L from the Tata 407)
2. Safari Dicor 2.2
3. Chevrolet Beat Diesel 1.0 tcdi
4. City 1.4 Idtec
In comparison, the NVH of 1.6 and 1.5 diesels of VAG doesn't bother me. Infact their performance and tractable nature makes up for it. Anyways most of us drive with our music on, don't we?

But my 1.23 lakh km run 1.3 DDIS200 in my ciaz is relatively quieter than its own sibling's in the SCross and Brezza. It also depends on the insulation I guess.

Polo/vento/rapid being the entry level models in their companies, I think they don't care much about providing better noise insulation.