Ertiga and Swift have been based on the same platform, but the two are completely different products. Ertiga is an MPV with a seating capacity of 7, while Swift is a hatch, which accommodate only 5. Swift uses a 1.2-litre K-series petrol and 1.3-litre diesel engine, while Ertiga uses a 1.4-litre K-series engine with same 1.3-litre diesel engine but with Variable geometry turbo and more power. So, both the car are different and it depends on you that you want a 7-seater family car or a daily commuter.
Maruti has announced offers on Wagon R, Alto 800 and K10, but there are no announcements about offers on Ertiga. But, you can expect to get some offers later in the month. For exclusive offers, please visit your nearest Maruti dealer to find out the details.