Mileage: At current 2016 prices, diesel cars mileage is generally 30-40% higher than petrol model. Petrol cars fuel expenses would be 40% more than diesel cars for city driving and 30% for highway driving.
Fuel Prices: About 20 years ago diesel price used to be half of petrol price. However, ever since the deregularisation of diesel prices, the gap between prices of petrol & diesel has come down from Rs.21/litre in 2013 to around Rs. 11/ litre in 2016, i.e. less than 15%.
Monthly running: Natural choice is a petrol car. But if your average monthly running is higher than 1,200-1,500 km a month purchasing of a diesel car would be economical.
Other Factors: Servicing costs, costs of spare parts and insurance costs are higher for diesel cars than petrol ones. Right from the cost of oil replacement to the battery and clutch plate, etc. all cost more in case of diesel cars. Also, the noise, vibration and harshness levels of petrol cars are lower than that of diesel cars. While diesel engines save with no spark plugs but they do get turbochargers which will push up maintenance costs.
Holding period: While one can hold the petrol car up to 10 years with reliability of usage, diesel cars can be held for about 7 years at the best.
Resale value: Diesel cars depreciates much faster than petrol cars. After 3 years, while petrol cars gets you about 60% of purchase value, diesel can get you at best 50% of purchase value, in the secondary market.
Pollution: Petrol driven vehicles are easier on the environment.
Conclusion: If your average usage is less than 1,500 kms per month PETROL CAR with lower capital cost, higher fuel costs and lower servicing, spares & insurance costs is suggested. If your average usage is more than 1,500 kms per month DIESEL CAR with higher capital cost, lower fuel costs and higher servicing, spares & insurance costs would prove beneficial.
About 20 years ago, Maruti was making only petrol cars and diesel cars were preferred only by taxi operators. The advent of CRDI diesel cars offering improved pickup, higher power, lower fuel consumption and reduced vibrations as well as lesser maintenance costs consumers preference shifted towards diesel vehicles. Today diesel cars share is as much as 40-50% of market. Maruti's lobbying for price preference for petrol cars and restrictions on diesel cars was not heeded to by central government.
With rapid increase in number of cars, year after year, cities are flooded with diesel cars increasing traffic congestion, non availability of sufficient parking in public places and above all pollution levels have crossed alarmingly to higher levels especially in Delhi. Despite banning 15+ year old cars, promoting CNG and banning SUVs with 2L+ capacities have only controlled the pollution growth rates only but pollution levels remained at higher levels. Reducing diesel & petrol price gap didn't yield much result. Now there is thinking to ban diesel cars & diesel SUVs throughout the country which will definitely happen sooner or later first in cities and rest of the country later.
As a responsible citizen, people should voluntarily opt for lower polluting, smaller or optimal power petrol cars only and contribute minimal pollution and help save environment.