What is your major requirement? Is it budget, space, service availability or refinement?
I don't think the Linea diesel, Fiesta diesel or Vento Diesel would fit in your budget (Last I remember, I was quoted 9.22L for the diesel fiesta. But then, I was looking at the top end model. I think there is a limited edition Exi that is slightly better than the base version but I don't think it's worth the price).
Budget:
I think it would be Swift Desire < Fiesta < Linea < Vento in terms of price.
Service availability:
The Swift Desire or the SX4 would be a good buy from the service availability point of view(However, there is no guarantee that you will get great service just because it's maruti
).
Space:
The Swift Desire has a big boot but a slightly claustrophobic cabin and a cramped back seat which is odd because the one thing that differentiates a sedan from a hatchback is the rear sear legroom which is always more in a sedan due the the extended wheelbase, ability to incline the seat more etc.
The in-cabin space of the Fiesta and the Linea is less as compared to the Vento (which in turn is slightly lesser than the city).
Refinement:
The Swift Desire has a cramped backseat and does not have sedan like refinement (for eg: thin door panels that I observed) as it is just a half-chassis car with a hatch attached. The Fiesta and Linea are more refined. The Fiesta is based on an older platform and has less goodies than the linea(which I guess has the most goodies from among the lot).
The build quality and paint job of the Vento is very good. Interiors are good too. The Linea is well built but the interior part quality leaves much to be desired. The fiesta build quailty is better than that of the Swift Desire.
I would say that the Linea and Vento are more refined as compared to the fiesta and much more that the Swift Desire. I don't know about the SX4 as I haven't test-driven one so far but I do expect it to be less refined that the Linea or the Vento.
). Few things which I liked.
