India differs from giant slow-growth and no-growth auto markets like the United States and Western Europe, and even from fast-growing markets like China, in that the emphasis is on small, low-cost cars — but with four doors, not two, and room for the extended family.

Image Rush hour in New Delhi. Analysts expect more cars to join or replace the 65 million scooters on Indias roads, with new ultra-affordable cars leading the boom. Credit... Jacob Silberberg for The New York Times

While the Indian upper classes are snapping up roomier models and even imports like Mercedes-Benz, first-time buyers will provide a big chunk of growth for years to come.

By 2013, CSM predicts, India’s market will expand an average of 14.5 percent a year, compared with just over 8 percent for China. CSM estimates that in 2013, the Chinese will buy 10.8 million cars, compared with 3.8 million in India, but says there is already a glut of local and foreign manufacturers in China, making India a more attractive long-term market.

If global manufacturers can figure out how to make small, cheap cars in India, they are expected to start exporting them to other fast-growing markets where the proportion of car ownership remains small — places like Southeast Asia, Africa and the Middle East.

But first they have to conquer this market. A. T. Kearney, an international management consulting firm, estimates that a car with a $3,000 list price could attract 300 million buyers in India by 2020. Of course, forecasters were bullish on China for decades before its growth finally took off. And economic upheaval or political change could stall India’s expected growth, too.

But the millions of Indians who will buy cars are likely to agree with Shuchita Bagga, who bought her first auto in July. “Budget was the most important thing,” said Ms. Bagga, 26, a trainee in human resources who earns about 375,000 rupees a year (about $9,500) and paid a little more than 235,000 rupees ($6,000) for it. “I’m not in a position to buy a big or an expensive car.”

In addition to new economy types like Ms. Bagga, car manufacturers are looking at India’s approximately 65 million scooter owners, mostly men. Currently, entire families commute on scooters, with the man of the house driving, his wife sitting side-saddle on the rear, and as many as three children wedged in between.