Electric Vehicles vs CNG Cars: Driving Tata’s Tiago EV And iCNG To Analyse Pros, Cons And Running Costs

With more and more EVs now starting to enter the mass-market segments, the question that comes up is -- should you still consider a CNG car?

By Jaiveer Mehra


1 mins read


Published on July 4, 2024

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  • EVs offer very low running costs especially when charged at home
  • CNG's have the advantage of faster tank-up times and having a petrol tank to extend range
  • EVs require greater running to make up the additional purchase cost

The mass market passenger electric vehicle (EV) story in India really picked up pace with the launch of the Tata Nexon EV over four years ago. Since then the market has grown with multiple offering from the likes of Tata, MG and Mahindra with prices for some even sitting in the sub-Rs 10 lakh bracket. The USP for EVs have been its very low running costs and zero tail pipe emissions compared to conventional petrol and diesel vehicles though you do pay a notable premium over the latter.


Also read: Tata Tiago iCNG AMT Review: Two-Pedal Convenience Meets Frugality

Tata Tiago EV and Tata Tiago CNG 1

While EVs are relatively new to the mass market segments, CNG has been offered for years.


However, the mass market segments have long offered an alternative to petrol and diesel promising both lower running costs and emissions - CNG. CNG cars, while pricier than their petrol counterparts, are still more affordable than EVs at the time of purchase so the question that comes up is, which is the right powertrain for you?

To answer that question, we have brought together the Tiago iCNG AMT and the Tiago EV. Why, you ask. Well they are almost identical in almost every way except for the powertrains and both are also automatic so they’re as close as possible which serves our purpose very well.


Also read: Tata Altroz Racer Review: Does This Hot Hatch Get Your Heart Racing?

Tata Tiago EV and Tata Tiago CNG 6

Tiagos ideal choice for this comparison as just the powertrain is the main difference between them

CNG vs EV: In-Car Practicality

We start things off with practicality and with these two Tiagos you can see just how different the packaging can get. The Tiago EV and Tiago CNG are identical in almost all aspects be it space inside the cabin or seating comfort though you do get a few more bells and whistles with the EV such as connected car tech, leather seats and keyless entry and go but that's besides the point.


Also read: Tata Motors’ EV Sales Drop To 18-Month Low In June: Find Out What Tata Attributes The Slowdown To

Tiago EV i CNG

Cabins are near identical in terms of design and space with the EV getting some additional features.


The EVs packaging advantage becomes apparent when you open the boot. In all CNG cars, the tank holding the CNG is placed in the boot so you get limited to negligible space in the boot for luggage. Tata has tried to address this with its new dual-cylinder technology which replaces the single large CNG tank with two smaller units under the raised boot floor. Sure boot space is down to just 107 litres from the petrol’s 242 litres but there is now space to actually be able to fit a few soft bags and even a medium size suitcase.


Tata Tiago i CNG 17

CNG tanks eat into the boot space; Tiago EV boot just down 2 litres compared to petrol


The EV meanwhile just loses out on 2 litres of space compared to the petrol Tiago which in reality makes zero difference. The battery pack sits below the cabin and boot floor so while you are seated slightly higher in the EV, you still get full use of a boot compared to a CNG car.


Advantage - EV.

CNG vs EV: Driving Comfort

Both cars here are automatics for the sake of similarity though the Tiago CNG does come with a manual gearbox as well. 


Also read: Tata Nexon EV vs Tata Punch EV: Sibling Rivalry

Right off the bat, the EV is the smoother powertrain of the two. There’s just a single gear and power delivery is linear and butter smooth. Power is also available a lot more immediately so acceleration too is stronger and with no engine up front you also feel fewer vibrations and there is no engine noise as well so even NVH levels are quite good. Of course you still have to deal with road noise and wind noise as in most mass market cars.


Tata Tiago EV and Tata Tiago CNG 47

Tiago EV feels lot more composed due to lower centre of gravity; lot smoother to drive as well


With the CNG you are still dealing with an internal combustion engine and a gearbox with multiple gears. This means there are more interruptions in the power delivery as you or in this case, the car’s computer and actuators row you through the gears in daily driving. The AMT gearbox which having made automatics a lot more affordable is not without its flaws either. Its slow to engage gears and in this Tiago iCNG AMT in particular holds onto first gear till at least 20 kmph. So that smoothness of the EV is lacking. You additionally also have to deal with engine noise and vibrations that can leak into the cabin via the steering, pedals or gear shifter.


Tata Tiago EV and Tata Tiago CNG 44

As with other internal combustion cars Tiago iCNG has higher NVH levels compared to EV.


The EV is also likely to feel the more stable of the two as we noticed driving the two Tiagos back to back. The heavy battery pack below the floor not only adds weight to the package but places the centre of gravity lower down so it feels more planted than its CNG sibling. Of-couse both cars handle potholes without much fuss though the EV does feel slightly more supple in rounding off the bumps.

Point again to the Tiago EV.

CNG vs EV: Topping It Up


It’s when you come to fill-up or charge-up times that the CNG shows its advantage. Yes EVs can be charged at home while you sleep at night and that is a big plus but there are still lengthy charge times involved. Charge times also depend on the model and the capacity it supports. Take this Tata Tiago EV from comparison. Tata claims a 58 min time for a 10-80 per cent charge using a 25 kW DC Fast charger though a full charge means that stretches close to the 1.5 hour mark. The optional 7.2 kW AC charger takes a longer 3.6 hours for a full charge charge so if you didn’t charge at home prepare to wait. Charging at home from a 3.3 kW wall box or 15 A socket takes about 9 hours to full.

Tata Tiago EV and Tata Tiago CNG 38

Fast chargers juice up battery quickly up to 80 per cent; last 20 per cent a lot slower


As you noticed, the charging options for EVs are quite varied. AC chargers generally range from 3.3 kW to 7.2 kW for mass-market EVs with some luxury car companies also offering an 11 kW unit. Similarly, the capacity for fast chargers range from 25 kW to over 100 kW. However as most mass-market EVs only support up to 50 kW DC fast charging, we’re not considering the more expensive super-fast chargers.


Tata Tiago EV and Tata Tiago CNG 34

Filling up CNG as quick as topping up petrol.


In comparison, CNG cars don’t generally take any longer than a petrol or diesel car at a petrol station. The only gripe people might have is lining up with the dozens of taxis that frequent CNG filling stations to top up the tank. This does mean that you could have to wait a while for your turn but even at its worst we don’t see you waiting more than half an hour to tank up.


Tata Tiago EV and Tata Tiago CNG 33

Waiting at CNG filling stations takes some time but still quicker than charging an EV


Advantage -- CNG.


CNG vs EV: Driving Range


Coming to the range and mileage, well the Tiago CNG has an advantage given that it can also be run on petrol. However, for most users CNG remains the primary motive fuel with petrol only ever being used in emergencies or to get to the nearest CNG station when out of gas. So considering this we are looking at CNG only running.  Our test of the Tiago iCNG AMT revealed an approximate figure of 19 km per kg combined for city and highway giving it an estimated range of about 150 km.


Tata Tiago EV and Tata Tiago CNG 42

Tiago iCNG AMT returned around 19 km per kg (combined) in our testing.


Of course these are not hard and fast figures with the level of traffic, terrain, heat and driving style also playing a factor in the car’s mileage. While our tests showed an overall range of close to 150 km, our general usage of the car saw it return widely different figures ranging from close to 100 km to about 145 km on a full tank owing to various factors.


The Tiago EV meanwhile offered 175 km of range in city use and about 205 km on Highway with the default regen setting of 1. Of course higher regen modes can help you eke out more range though overall we estimate a range of about 180-185 km based on our testing. Of course this is for the Tiago EV LR with the 24 kWh battery pack so if you go for the MR model with the smaller battery expect range to also drop.


Tata Tiago EV and Tata Tiago CNG 49

Tiago EV offered a combined range of about 185 km with regen set to 1.


Where things get tricky is that with an EV if you run out of juice you are done for and will have to resign yourself to waiting at the nearest EV charger. The CNG meanwhile, if you set-off with both petrol and CNG tanks on full you could get over 400 km of additional range from running on petrol once the CNG runs out.

City 18.86 km/kg175 km
Highway 20.07 km/kg205 km
Overall 19.12 km/kg185 km


Advantage – CNG

EV vs CNG: Cost Analysis


Now we come to the most important aspect that is the cost analysis between the two powertrains. Starting with the CNG, the Tiago iCNG AMT sets you back about Rs 10.1 lakh on road in Mumbai and a full tank on CNG at the rate of Rs 73.5 / kg (price at time of testing) costs around Rs 600. The twin tanks hold around 8 kg of CNG in total. Divide the cost of a full tank with a range of 145 km we get a running cost of about Rs 4.14 per km.


Tata Tiago EV and Tata Tiago CNG 8

EV has the heftier price tag - about Rs 2.5 lakh more than the CNG in this case.


Moving to EVs, well it's a little more complex. Home charging is the most efficient and affordable way of charging an EV with rates going as low as a claimed Rs 1 per km if not lower. Of course electricity to home connections are provided at slab rates so ascertaining an accurate price is tough.


Tata Tiago EV and Tata Tiago CNG 41

Home charging an EV really brings down running costs to as low as Rs 1 per km.


To simplify things for this comparison we’ve taken the highest slab rate to estimate the highest EV charging cost for charging home which for Mumbai’s BEST is Rs 11.73 per unit. Multiply the cost per unit by the battery capacity and you get a total cost of Rs 281.53 for a full charge. Divide this  by the estimated 185 km range returns a figure of about Rs 1.5 per km which is a lot lower than even a CNG car.


  CNGEV (Home charging)EV (public fast charger)
AFuel PriceRs 73.5/kgRs 11.73 per unit*Rs 22 per unit
BCapacity8 kg approx24 kWh24 kWh
COn-road price (approx)Rs 10.10 lakhRs 12.60 lakhRs 12.60 lakh
DRange145 km (CNG only)185 km185 km
ECost for Full Tank/Charge (approx) (AxB)Rs 600Rs 281.5Rs 528
FCost per km (E/D)Rs 4.14Rs 1.5Rs 2.93
G50 km daily running cost (50xF)Rs 207Rs 75Rs 146.5

*BEST Mumbai 500 unit+ consumed rate


Public fast chargers will of-course bump this up with cost per unit generally starting around the Rs 15 per unit mark with most mid-capacity charger prices hovering in the Rs 20-25 mark. Going with a rate of about Rs 22 per unit you would look at a charging cost of Rs 528 for a full charge which would return a cost per km of Rs 2.93.


Tata Tiago EV and Tata Tiago CNG 35

CNG running cost is higher at Rs 4.14 per km but initial investment is lower than EV


Then of course there is the price of the Tiago EV itself which at around Rs 12.6 lakh on-road in Mumbai costs about Rs 2.5 lakh more than the iCNG AMT. Divide the additional outlay with the difference in cost per km of two cars and you realise that you will need to cover almost 95,000 additional km to make up the cost difference. So if you cover 15,000 km a year you’re looking at roughly 6.3 years to make up the additional investment.


  Break Even Km (Home charging)Break Even Km (Public fast charger)
ADifference in car priceRs 2.5 lakhRs 2.5 lakh
BDifference in per km costRs 2.64 per kmRs 1.21
CKM to Break Even (A/B)94,697 km2.07 lakh km
DTime to break even (15,000 km yearly) (C/15,000)6.3 years13.8 years

Of course, the EV charges are based on the highest chargeable rate and could be much lower depending on the slab rate applied, electricity service provider and the electricity consumption at home.


Also matters such as depreciation, service costs and loans also affect this calculation but we have not taken those into account. What we can say is that you are expected to save more on EVs when it comes to service costs compared to its internal combustion counterpart - that is for general wear and tear parts and not specialty repairs.


CNG vs EV: Verdict


So now the question that needs answering is should you buy a CNG or should you buy an EV. Well starting with the electric choice, most budget EVs make sense for city driving where range is not a big issue and access to chargers is easier than out on the highway. Running costs are very low as you can see and EVs will also feel peppier to drive and more comfortable as well such as in this case.  Then there is also the packaging advantage the EV has over its CNG sibling. With no tank in the boot you get to use the full boot space to load up luggage while in the CNG space is limited to non-existent at best. However, for that added practicality, low running costs and smoother performance the EV is weighed down by its long charge times and substantial additional investment that means you will have to rack up the miles to make up the additional investment.


Tata Tiago EV and Tata Tiago CNG 5

EV makes sense with high yearly running to recoup cost; CNG is still a viable alternative.


The CNG is the more compelling option to own especially when you factor in aspects such as fueling up, range and initial investment. Yes, there is some waiting involved especially when you line up with the taxis at the pump but it's still a lot shorter than waiting for the EV to charge. Tata’s new dual-cylinder technology also means that this Tiago CNG also offers some boot space compared to most rivals. The fact that there is a petrol tank that you can switch too in case you run out of CNG is also a big plus when you go outstation. Of-course this will cause your cost per km to be affected which will change the entire calculation as well.


So which should you buy? Well, EVs only starts to make sense if you are considering really clocking in the miles with the higher initial investment meaning you are looking at a few years to make back the additional amount spent. Otherwise, its the CNG that makes more sense as a daily runabout. Of course if you only plan to use the car for the bare minimum running, you might as well go with petrol. 

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