NEW DELHI, Dec. 29 -- Ignis is not just another car that Maruti Suzuki is adding to its fleet of 18 models. The car maker, which sells one in every two cars in India, will sell the Ignis from its Nexa dealerships, and the car is especially designed to attract the young car buyer. India has the world's youngest car-buying population - 27% of the car buyers are under the age of 29 - and Maruti's rivals have tried to get a grip of this section. Maruti didn't have much to do - its cars were boxy, and known for mileage, trust and reliability. India is also the world's fourth largest new car market, expected to overtake Japan by 2020 to become the third largest. It also has a large used-car market. Maruti's rivals launched cars to attract the you...