Why Petrol, Diesel, and CNG Engine Offers Different Mileage? —Choosing the Right Variant

Choosing the appropriate fuel type for a car is a major decision for most prospective buyers. Amongst the options available, there are petrol, diesel, compressed natural gas (CNG), and electric vehicles (EVs) and each has its pros and cons. Traditionally, petrol cars have been the preferred choice of many buyers due to their ease of use and convenience, whereas diesel vehicles have been the favorite of long-distance travelers because of their better fuel efficiency. On the other hand, CNG vehicles are liked for low fuel costs, and EVs are increasingly becoming popular among the environment-conscious consumer due to their low emissions.

The Tata Nexon is an extremely popular compact SUV and is available with all four fuel types; thereby offering the best chance of a head-to-head comparison to arrive at which is the best one by giving what one wants, comparing all aspects of ownership as purchase price, running fuel, maintenance cost, and then finally over time total cost of ownership for prospective customers.

Initial Costs

The initial cost of a vehicle is one of the most important factors in the decision-making process for most buyers. The upfront price varies across different fuel types due to differences in the technology and components used. Below is a comparison of the on-road prices for different variants of the Tata Nexon:

It also offers the cheapest entry at point of purchase and petrol variant, but one of the costs associated with it may be justified to pay extra money for running either on a diesel or CNG. Some also prefer running an EV according to personal preferences.

Five Years of Fuel Expenses

Fuel expense is one of the highest recurrent costs of owning a vehicle. These costs depend on the average mileage covered by the vehicle and the fuel price. Assuming that an average annual driving distance of 30,000 km has been covered (or a total of 150,000 km over five years), the costs for each variant can be determined based on their respective fuel prices and average mileages.

Here is an analysis of the fuel costs for each type of fuel:

The petrol vehicle has the highest expense costs among all the variants, with a diesel and CNG alternative that is cheaper in running costs. Most surprisingly of all, the variant of electric vehicles is the cheapest form; it has lower running costs because electricity costs much lower per unit compared to gasoline.

Maintenance Costs Over Five Years

Maintenance costs are another important factor to consider while calculating the total cost of ownership. Servicing and repairs are essential to prolong the life of a vehicle and ensure it functions optimally. The estimated maintenance cost for each variant for five years is as follows:

 
Petrol vehicles are mostly the cheapest to maintain, since fewer complex parts need to be serviced regularly. Diesel and CNG variants have slightly more expensive maintenance costs, mainly due to the more complex nature of the engine and exhaust system. EVs generally incur fewer maintenance interventions (owing to fewer moving parts) but still incur periodic costs related to brake fluid checks, tire maintenance, and alignment, though these are generally lower than traditional fuel vehicles.

Total Ownership Costs

While calculating the total cost of vehicle ownership, one needs to factor in the initial purchase price, fuel expenses over a period of time, and maintenance costs. Below is the break-up of total cost of ownership over five years for each variant.

                                  
Total cost of ownership reveals that CNG, while having the lowest in total cost among traditional fuels, has a competitive cost, as it is equally comparable with the total cost of ownership. EVs, on the other hand, though more expensive as an initial purchase, provide savings in costs of fuel, making long-term savings possible, considering the high initial investment for the same.

High Mileage Analysis: Driving Patterns

For the high mileage buyers, who drive extensively, things are very different in economics of vehicle ownership. Assume a driver travels 2,000 km per month. That translates to a total of 120,000 km over five years. The costs of running each variant is then recalulated. In the following pages, some estimates for high-mileage drivers are shown:

For high-mileage drivers, the EV variant is the most cost-effective option because of its extremely low fuel costs. Diesel, though more fuel-efficient than petrol and CNG, still does not match the long-term cost-effectiveness of EVs. CNG vehicles also save a lot compared to petrol variants but still lag behind EVs.

Break-Even Analysis

If a higher-cost variant of the vehicle is considered, such as CNG or EV, it is necessary to know how long it would take to recover the extra cost of the vehicle through fuel savings.

• CNG vs Petrol: The break-even point is reached after around 25,000 km of driving, given the additional upfront cost of ₹70,000 for the CNG variant. For a driver with moderate usage, this could be achieved in about two years.
• EV vs Petrol: The EV has an added initial cost of ₹3.76 lakh over the petrol variant. Break-even is achieved after travelling 51,000 km, which may take around four years with high mileage usage.

Performance and Practicality

The same fuel type offers different driving experiences and practicality:

• Petrol: Petrol engines provide smooth performance with good pick-up and high revs. Thus, they are perfect for city driving and short distances. On the other hand, running costs are a little high and also have more impact on the environment due to CO2 emissions.
• Diesel: Diesel engines have great high torque and better mileage characteristics, making them ideal for high way driving and long-distance travel. High initial cost and further risk of restrictions in city for diesel vehicles may be deterring some buyers.
• CNG: CNG is a cleaner fuel with lesser emissions, hence it is cleaner than petrol and diesel. However, CNG vehicles usually have lesser boot space because of the gas cylinder and have lesser power output, which can hamper performance, especially in hilly areas.
• EV: EVs are the most environmentally friendly option as they produce no tailpipe emissions and are supported by government incentives in many regions. However, they are more expensive upfront, have a much shorter range than traditional fuels, and potentially high battery replacement costs after the warranty period can be drawbacks.

Environmental Impact

The environmental impact of each fuel type differs:

• CNG is less polluting than petrol and diesel but still emits CO2.
• EVs are the greenest option in terms of emissions during operation. However, the environmental impact of manufacturing and disposing of lithium-ion batteries is a concern for some critics.

How does mileage get affected for different fuel types?

The mileage of a vehicle is significantly influenced by the type of fuel it uses. Here’s a brief overview of how different fuel types affect mileage, particularly for the Tata Nexon:

Petrol

• Mileage Range: The Tata Nexon petrol variants achieve a mileage between 17.01 kmpl and 17.44 kmpl.
• Factors: Petrol engines typically deliver good performance and responsiveness, but they may have higher running costs compared to diesel due to lower fuel efficiency.

Diesel

• Mileage Range: Diesel variants of the Nexon are more efficient, with mileage figures ranging from 23.23 kmpl to 24.08 kmpl.
• Factors: Diesel engines provide better torque and fuel efficiency, making them ideal for long-distance driving. They tend to be more economical over long distances despite higher initial costs.

CNG

• Mileage Range: The CNG variant offers a mileage of about 17.44 km/kg.
• Factors: CNG is generally cheaper than petrol and diesel, leading to lower fuel costs. However, CNG vehicles may have reduced power output and less boot space due to the gas cylinder.

Electric Vehicles (EV)

• Mileage Equivalent: While not directly comparable in traditional km/l terms, EVs have very low running costs, often translating to about 1.30 per km based on electricity consumption.
• Factors: EVs are the most efficient in terms of energy use per distance traveled, with zero tailpipe emissions, making them environmentally friendly.

What's the difference in all three engines that gives different mileages

The differences in mileage among petrol, diesel, and CNG engines in vehicles like the Tata Nexon can be attributed to several key factors, including engine design, fuel properties, and operational characteristics. Here’s a breakdown of how these elements influence fuel efficiency:

1. Engine Design and Technology

Petrol Engines: Typically have a higher RPM range and are designed for quick acceleration. They often feature smaller displacement (like the 1.2L turbo petrol in the Nexon), which can lead to lower torque compared to diesel engines. This results in a mileage of around 17.01 to 17.44 kmpl.

Diesel Engines: The Nexon’s diesel engine (1.5L) is built for efficiency and torque, providing better fuel economy (approximately 23.23 to 24.08 kmpl) due to its higher compression ratio and turbocharging. Diesel engines are more efficient at converting fuel into energy, especially during long-distance driving.

CNG Engines: CNG variants also utilize a similar engine design as petrol but are optimized for gas combustion, achieving about 17.44 km/kg. The energy density of CNG is lower than that of petrol or diesel, which can affect overall mileage.

2. Fuel Properties

Energy Content: Diesel fuel has a higher energy density compared to petrol and CNG, meaning it provides more energy per liter consumed. This is a primary reason why diesel engines generally achieve better mileage.

Combustion Efficiency: Diesel engines operate at higher compression ratios, leading to more complete combustion of fuel, which enhances efficiency and reduces fuel consumption.

3. Operational Characteristics

Driving Conditions: Diesel engines excel in highway conditions where their torque can be fully utilized, while petrol engines may perform better in urban settings with frequent stops and starts.

Weight and Load: Diesel vehicles often handle heavier loads better due to their torque characteristics, making them more efficient under load compared to petrol or CNG vehicles.

CarBike360 Says

The right Tata Nexon variant depends on individual buying habits, budget, and environmental considerations.

For drivers who cover low mileage per month (500–1,000 km), petrol or CNG variants provide excellent value with lower upfront costs and reasonable running costs. CNG is a good mix of affordability and practicality for moderate mileage drivers (1,000–1,500 km/month).

For high-mileage drivers, who cover more than 2,000 km per month, the EV variant is the most economical as it has lower fuel costs, though at a higher upfront investment.

Ultimately, the decision should be based on a careful evaluation of personal driving patterns, budget, and long-term ownership goals. Whether it is the performance-focused petrol models, the cost-effective CNG options, or the eco-friendly EVs, each Tata Nexon variant offers a compelling proposition depending on the buyer's needs.