Petrol prices have risen five times over the last year.
The differential between the two fuels stands at Rs 25.51 a litre, up from Rs 10 in April 2010, prompting an increasing number of consumers to opt for diesel cars.
Industry estimates suggest diesel vehicle sales grew 35 per cent last financial year to account for more than 47 per cent of the overall passenger vehicle sales.
Petrol car sales dropped by 15 per cent.
RC Bhargava, MSIL chairman, had earlier said, "In the current year, we are trying to bring down this decline to six per cent at Maruti Suzuki, but still, we'll be selling about 50,000 petrol cars less. We have 40 per cent of our petrol engine capacity lying idle at the Gurgaon unit."