Its closest rival remained Hyundai Motors India Ltd with a 15.18 percent share, while Mahindra & Mahindra (10.15 percent) overtook Tata Motors (7.94 percent) to the third spot.
Japanese major Honda was in fifth place with a market share of 5.36 per cent, just ahead of Toyota's 5.14 percent.
Domestic sales of passenger vehicles, which includes cars, utility vehicles and vans, declined 6.05 percent to 25,03,685 units in the previous financial year from 26,65,015 units in 2012-13, according to data from the Society of Indian Automobile Manufacturers (SIAM).
Maruti's market share increased from 39.43 percent in 2012-13, when Hyundai's was 14.39 per cent, Mahindra's was 11.65 per cent and Tata Motors 11.79 percent.
During FY14, Maruti's passenger vehicle sales grew marginally to 10,53,689 units from 10,51,046 units in 2012-13. Hyundai sold 3,80,253 units in FY14 against 3,83,611 units in FY13.
Mahindra's passenger vehicle sales were down 18.14 per cent to 2,54,344 units from 3,10,706 units.
Tata Motors sold 1,98,812 passenger vehicles in FY14, a drop of 36.77 percent from 314,464 units.
Honda Cars India, which had a good year riding on its compact sedan Amaze and the new City model, posted growth of 82.81 per cent to 1,34,339 units.
Toyota Kirloskar Motor, which has been hit by labour unrest at its two plants in Bangalore, sold 1,28,811 units in 2013-14, down 22.17 percent.
In the car segment, Maruti's sales in FY14 grew 3.38 percent to 8,90,455 units, while that of Hyundai was down 0.86 percent to 379,555 units.
Honda's car sales zoomed 82.17 percent to 1,33,321 units, while those of Tata Motors fell 38.64 percent to 1,07,187 units.
Toyota Kirloskar's car sales were down 21 percent at 56,865 units.
During the previous financial year, Mahindra's sales of utility vehicles dropped 16.86 per cent to 2,19,421 units.
In the motorcycle segment, market leader Hero MotoCorp's sales grew 1.16 per cent to 54,25,118 units in 2013-14 from 53,62,730 units a year earlier.
Rival Bajaj Auto had a 14.79 per cent decline in bike sales to 20,99,230 units from 24,63,863 in 2012-13, while those of Honda Motorcycle and Scooter India were up 39.5 percent to 16,55,548.
In scooters, market leader Honda Motorcycle and Scooter's sales grew 33,99 percent to 19,02,859 units, while that of Hero MotoCorp were at 6,90,079 units, up 25.51 percent.
Chennai-based TVS Motor Co posted a 7.73 percent increase in scooter sales to 4,56,975 units.