The decline in car sales, is mainly because most citizens are not confident about the future. Owning a car is fairly expensive, and the value of a car will decline every year.
Increasingly indian society and government is extremely prejudiced against older people, they often find that they there are no jobs available, and their orders are also diverted to younger people.
Most young people in metro cities prefer to hire cabs, since driving a vehicle is also fairly stressful
Hence many do not want to purchase any car, resulting in decline in car sales