[SS-Traveller]

Kitna Deti Hai, or the common query in Hindi about the real-world fuel efficiency of a car, is one of the first questions most Indian customers ask, when setting out to buy a car.

Our obsession with the fuel consumption of our vehicles has to do mainly with saving a few rupees at the fuel pumps - a trend that started with increasing fuel prices during the oil crisis of the 1970s, and persisted through the next few decades as smaller and lighter cars with increasingly more fuel-efficient engines and cleaner technologies (fuel injected petrol engines, common rail diesel engines) appeared in the market.

When designing a car and an engine in the last quarter of the 20th century, the primary focus was on fuel efficiency. To this end, vehicle weight and size were reduced, engines were downsized, and newer engine & combustion technologies were introduced.

But as the oil crisis blew over, a new crisis, that of environmental pollution, appeared over the last 3 decades. Fuel efficiency was not the primary criterion for designing engines any more. The engines with the least emissions, measured in grams per kilometre, were suddenly the best engines.

Common sense indicates that a higher fuel efficiency leads to lower emissions of greenhouse gases (GHGs), especially CO². To this end, engine designers started making mini-engines with progressively smaller displacement, even as governments around the world mandated that smaller displacement engines get bigger tax breaks (Japan with their 550cc (later allowed to increase to 660cc) engines, and India's 1.2L(P) / 1.5L(D) rule (10 years of the Small Car rule (<4-metre, <1.2L petrol, <1.5L diesel) : Has India benefitted?)).

But then, apart from fuel efficiency and emissions, a third factor popped up on the horizon - the consideration of occupant safety in the event of crashes. Cars started to grow bigger and heavier, with stronger reinforcements and more complex features that, in simple terms, added more inches and kilograms to newer cars. Japan also altered their kei car rules and reduced incentives for buyers of smaller cars and engines.

Yet, in India today, our engines are getting smaller (albeit more powerful on paper), even as our cars get heavier due to the need for better safety tech. When buying a car, we are led to believe that an engine with a smaller displacement (e.g. 1.0L instead of 1.5L) is more fuel efficient (and we also assume that such smaller engines also have lower emissions). In real-world usage, however, we hear of wildly varying reports of fuel efficiency from engines of smaller displacements. The 1.0L Ecoboost engine that Ford introduced some years ago flopped severely, not only in India but even in the USA, due to reliability issues as well as fuel efficiency - even though it was technologically very advanced.

Originally Posted by SS-Traveller

Ford

...1.0L EcoBoost engine on display...
...is it that the EcoBoost engine uses synthetic oil for engine lubrication, and the belt material is somehow compatible with synthetic oils? If the latter is the case, I dread to think what a top-up with mineral oil (again, the typical Indian chalta hai scenario when it comes to vehicle maintenance) would do to the timing belt.
...
...improving fuel efficiency. The weight gained by using cast iron is far less disadvantageous than the thermal efficiency gained by using it.

The little Suzuki Alto K10, or the jellybean Zen, were never known for their fuel efficiency, and the WagonR 1.1L went further per litre than the new versions with 1.0L engine.

The 1.2L petrol engine in the XUV3OO is far less fuel efficient than its siblings which are both larger and have larger displacement engines.

Originally Posted by SS-Traveller

So we have a heavy car with a small 1.2L petrol engine which is neither fuel efficient nor seriously peppy...

OTOH, the Tivoli available in Australia has a 1.6L petrol engine (and a 1.6L diesel too), is 4202 mm long with 423 litres of boot space, and returns a fuel efficiency of 11.62 kmpl (8.6L/100km) for the urban cycle and 18.18 kmpl (5.5L/100km) for the extra-urban cycle (i.e. highways) for the petrol engine (combined cycle = 6.6L/100 km).

We are now hearing reports now of the 1.0L Hyundai Venue returning single-digit kmpl figures in city usage.

[SS-Traveller]

It stands to reason (and basic chemistry) that an engine with poor fuel efficiency would also be high on carbon emissions, and fuel consumption and CO² emissions are linearly related (I am not sure whether higher fuel consumption = higher emissions of other GHGs such as NOx / SOx, because emissions reduction devices such as catalytic converters and EGRs).

For a given vehicle weight, a certain power & torque output are required from its engine - which can come from either a large displacement engine in a lower state of tune, or a smaller engine tuned to extract higher bhp and lb-ft per cc. In the latter event, we seem to consistently find that a poorer fuel efficiency is the result - which equates to poorer GHG emissions.

So the big questions that we need answers to, are:

1. If an engine with smaller displacement turns out to be less fuel efficient than a larger engine, why are we insisting on using smaller displacement engines worldwide?
   -
2. Are engines with lower displacement (and higher bhp output per cc) less polluting (and more fuel efficient) than bigger displacement engines under different traffic conditions than what we see in India?
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3. In other words, is the Indian urban driving cycle so different from that in Europe or the rest of South-East Asia, that the mileage figures of small hypertuned engines are so poor? Or does it have to do with fuel quality?
   -
4. Apart from higher COx emissions, do smaller engines with poor fuel efficiency conforming to the newest emission laws still have higher emissions of other GHGs?
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5. Are we in India (and Japan & Europe) invested too deeply in technologies that help create little engines with big power outputs, and it would be an expensive affair to go back to having bigger engines?
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6. When buying a new car, which is most important?
   - the displacement;
   - the power (bhp) and torque (N-m) numbers;
   - the fuel efficiency on paper (ARAI certified mileage figures); or
   - the real-world fuel efficiency as reported by actual users.

[GTO]

Thread moved from the Assembly Line to the Indian car scene. Thanks for sharing!

Will go to homepage on Monday

Always been an engine guy, so voted accordingly.

[rajshenoy]

Displacement - needed for relaxed and stress free long term life( depends on weight of the vehicle)

Power - I prefer healthy torque at lower RPMs translating into lesser gear shifts and comfortable drives. However those enjoying high speed dash(beyond 140kmph) do vouch for those high revving engines(I rarely get to cross those speeds)

Refinement - though not part of this poll, I rate this high. A smooth and refined engine is what I enjoy as compared to some engines which appear "work in progress".

Gearbox combination - Again very important, it's like a marriage to extract best out of the engine

[fhdowntheline]

I think it depends on the usage. If I am looking at a car for highway runs, power/ torque are more important. I would look at power/ torque that is available in the cruise range of speeds rather than top end. But if I am looking at a car that would squeeze thru gaps in the city and be a safer option than 2 wheelers, then fuel efficiency may be more important.

[xjosephjacob]

What actually matters to me is how the numbers on the paper- Displacement, Power & Torque, and ARAI certified fuel efficiency- translates on the road.

Being a 'early majority' in the product life-cycle (and especially since I don't have financial muscles to own multiple cars for specific use cases) I try to find a balance between longevity, economy and performance with a specific focus on reducing the projected total cost of ownership.

So how do I do it ? No rocket science here, I just wait patiently doing my researches (including spending at-least 250-300 km with the car). Sometimes I end up way off the mark too. That's life

[Simhi]

We Indians evaluate in most purchases whether we are getting value for the money paid. Therefore, given a choice for comparing vehicles within a price range, I would prefer a vehicle with higher displacement, more power and torque at lower rpms and higher real-world fuel efficiency.

Voted for displacement. When purchasing Yaris, I wanted my next vehicle to have at least 1.5L engine. CVT transmission was a plus at it gives better fuel efficiency and we can cruise at triple digits at lower rpms.

[lapis_lazuli]

Very appropriate thread. For sure, a small engine has to work harder and burn more gas for the same, workable grunt needed for effortless urban commute.

I need to emphasize urban, that's practically where everything is concentrated and measured: drivability, pollution, pollutants, everything. It is a vicious cycle : a "frugal" engine good for ARAI on highways, trying to be frugal in the city, irritates the driver because both power and torque are "frugal" at almost half the turbo spool/boost region, lower gears, more gas more COx and we cry hoarse how it is a bad mill!

These are more polluting than a larger relaxed engine! That is also when emissions automatically fall into place : optimal and bare minimum fuel burn/combustion.

It is always the right engine size, and an informed decision based on the power band that you would mostly use as per your daily needs. The others fall into place automatically IMHO. Mileage figures : ARAI or hearsay, are not as helpful.

[Sebring]

For me efficiency is very important. Can't highlight that enough. Running a car is indeed very expensive over here and I need maximum bang for the buck. Diesel is my fuel of choice. My Tata Nexon D is a 1497 CC with 108.5 BHP output, yet returned 24KMPL on my Chennai trips. In the city it averages 20KMPL, much to my delight. The torque power on tap is just fantastic. So, if ever I replace this car it will be with another Nexon.

[gkveda]

There are multiple very important parameters to be prioritised while in the market but from what is given as options,only two stands out.

Power and fuel efficiency are two moost important factors for me.

How does it really matter what ARAI says about the car and its fuel efficiency? Anyways in real time, no car gives the numbers mentioned by them as they are not real world scenarios and IMHO, biased too. Hence, I rely only on owners experience and the FE they got in real-time.

Regarding displacement, yes it is mostly proportional to the power delivered. However, in recent times, there are cars with lesser displacement yielding higher power. But ultimately, as end user, i would be more interested in power delivery rather than displacement.

[a4anurag]

"There is no Replacement for Displacement!"

I believe in this and moreover, with a higher displacement engine, the power & torque figures are much better anyway (I'm focusing on diesel only here) leading to better driveability and fuel economy.

I feel a small displacement engine will feel strained in a larger vehicle and won't be fun to drive. And a 3-cylinder engine is not acceptable, a 4-cylinder is a must.

While looking for a new car, I'll focus on how the power & torque is delivered and not figures on paper. At the end of the day, if driveability is poor, everything will be bad!

[Cessna182]

A bigger engine with a high torque at a low RPM (<2k) can deliver fantastic mileage. The reduction of engine size in India has led to products which need to be revved continuously to extract any driveability. This leads to more fuel consumption.

Also, the regulations like the insurance rates being different for cars with a bigger engine lead to incentives for manufacturers to create smaller displacements.

As for emissions, I don't think there's a proper standard test yet in India. PUC is a very old test. The goal should be to measure emissions in standard driving conditions like with full load, AC and at city speeds of less than 30 kmph.

[ruzbehxyz]

Have voted for power and torque because that's what I like the most.

Over last few years, the displacement has gone down and the power and torque has remained same or increased. This has led to controlling the emission as well.

A typical example is the 2.0 L new Ford Endeavour which produces 420nm of torque on a 2 litre engine. Although powerful, but some still complain as they compare it with the 3.2L engine producing 470 nm of torque.

[King_pin09]

Being a long distance driving guy, I believe displacement plays a very important role in the drivability and overall serviceability of a vehicle. Whilst BHP and NM numbers determine the overall performance in terms of acceleration and top speed, I do understand most of it remain unused for a substantial part of its life time. There exist several small engines which can churn out higher Bhp and Nm numbers albeit under the assistance of turbo charger or a revised configuration or otherwise. Such puny engines are under heavy strain which reflects in their feedback and driving manners.

On the other hand, a larger N.A engine with all 4 pots in place, can cruise comfortably all day, but under much less strain thus enhancing the driving experience and the overall service life of the machine.

[Hayek]

Don’t think that the world would be moving towards smaller displacement turbo petrols unless there was an actual real world benefit to having those engines.

Of course one reason could be that the “real
world” tests carried out in developed markets favour small displacement turbo petrols while that may be the same in Indian urban conditions. After all, an urban cycle in California will include freeway miles at 40-50 mph at 20 C external temperature, while the urban cycle in Mumbai is largely 20 kmph drives at 32 C temperature.

In my own experience, my Superb 1.8 TSI did give reasonable urban mileage of about 7 KMPL - which is not dramatically different from what we get on our 1.6 l NA Vento. While recognising that the Vento is largely chauffeur driven, and spends more time in market areas, there does seem to have been a mileage advantage from the 1.8 TSI, when benchmarked against the power and torque it delivered.

The downside with turbo petrols is that they cry out for drivers to wring them - and then give very poor efficiency when wrung. Drive a TSI gently, and it will give you stellar mileage - push it and there is a cost associated with the kick you get.