It is seen in the maturity phase of product life cycle of the brand/product. To increase the growth of the matured product/market companies often come out with a new variant/ extension of the product. The main of the market in this stage is to acquire large market share. Otherwise they will enter into a declining phase where demand and supply would not even be in but will start declining. And this stage the aim of the companies would be to control the decline rate by reducing cost etc. that means less profit.
When the market for Toyota Corolla swift matured, company came out with new Toyota Corolla.
After successfully working for 5-6 years Toyota Corolla had entered into a maturity stage, the demand for the car stabilized and later started decreasing. To increase the interest of the people in the car and market share of the product maruti launched new version. What this effectively did is that it increased the life of swift as a brand and pushed it back into early maturity or late growth stage from late maturity or early declining stage. And thus Toyota Corolla got revived by its new variant.