Best way to find the answer to this question is to know the difference between petrol and diesel version of the car. Earlier diesel cars were having discomfort of high noise as compared to petrol cars. But, Now a days, Comfort level is almost same in both the Petrol and Diesel versions of the car. Also maintenance of the diesel cars is also become equal to that of diesel cars.
Now the main point is the difference in the cost of ownership. So, we will calculate total expenditure occurred for both versions of the car.
We are assuming following points
1. For petrol cars
Cost after 5 years = initial cost + running cost – remaining value
= 5,00,000 + (60/18)*1000*12*5 – 2,50,000 = 4,50,000
2. For diesel cars
Cost after 5 years = initial cost + running cost – remaining value
= 6,00,000 + (50/22)*1000*12*5 – 3,00,000 = 4,36,363
So, in this case, diesel car is cheaper by (4,50,000 – 4,36,363 = Rs. 13,636) than petrol version of the car.
This is sample calculation only, if you want to own a second hand car for 5 years. You can change the above data as applicable in your case and calculate cost of ownership for your car.