All the models you have shortlisted have their highlights and weaknesses. The Maruti Suzuki Brezza is a well-rounded vehicle that excels in space and comfort. Maruti's service network is a huge plus in its own right. However, as you rightly identified, the Brezza is not exciting to drive. This Maruti Suzuki car's performance is fine in city driving conditions, and it will cruise comfortably on the highway. But the engine lacks punch in case that's important to you. 

If strong performance and good handling are requirements, the Skoda Kylaq and Mahindra XUV 3XO are the ones to be most interested in. Both models are good to drive, but fuel economy could be a concern in bumper-to-bumper city driving. 

We feel you will find a good balance in the Hyundai Venue 1.0 Turbo DCT. The engine is strong enough, and the gearshifts are also nice and quick. DCTs do tend to fumble at low speeds and aren't as smooth as torque converter autos. Although, it's not really an issue and surely not to the extent of avoiding the gearbox type altogether. 

Fuel economy should also be better than what you'd get with a torque converter.  The new Venue is also quite a wholesome package. The cabin is quite spacious, and the material quality is impressive. 

Yes, you are right, your short drive in Mumbai traffic won’t allow the diesel particulate filter (DPF) of Mahindra XUV 3XO to reach the temperatures. It needs to ‘light-off or regenerate properly to burn off the soot which will accumulate in your DPF and trigger a malfunction warning. 

The way to raise the exhaust temperature and subsequently heat the DPF to its ‘light-off’ point is to run the engine under a steady load. You should plan a long drive at least once a month, with around half an hour of continuous driving at around 50-60kph. 

Use a gear that keeps the engine between 2,000 to 2,500 rpm and drive steadily without hard acceleration or braking. 

The aim is to drive consistently so that the exhaust temperatures can stabilise and you can complete the regeneration process without interruption. Since you live in Powai, the Eastern Expressway is not far away and can be a convenient stretch for you to clear your DPF periodically.
 

If you are getting a good deal, go for the Kia Seltos HTX iVT. The new Seltos is bigger and fresher but gets the same engines and is likely to be at least a lakh more expensive. 

Yes, your resale will be hit once the new model comes out, but that can be compensated with the good deal you get on the outgoing model. The Mahindra XUV 3XO is a smaller car than the Seltos, so it will be a step down in that sense.
 

Since your usage is limited, the premium you will pay for a CNG or diesel version over the turbo-petrol might not make sense. Hence, stick to their turbo-petrol versions only. Both, the Mahindra XUV 3XO and Skoda Kylaq are great options, with strong engines, a comfortable ride and confident handling. 

The XUV 3XO is more spacious, while the Kylaq has a bigger boot. The Kia Syros is an excellent, well-rounded car, too, but its entry-level variant, which is decently equipped otherwise, doesn't get a sunroof. 

Hence, since you want a sunroof, within Rs 12 lakhs, the Mahindra XUV 3XO AX5 is the one for you.

The Tata Altroz diesel falls within your budget. Its ride and handling balance is excellent, and you are also likely to appreciate its audio system. 

Yes, its engine doesn't have the same punch as the VW Ameo TDI's, but you can expect it to be very efficient. 

An entry-level Mahindra XUV 3XO and Hyundai Venue are also options you can consider for their strong and refined powertrains. But you will have to look at after-market options for a satisfactory audio experience.
 

Since mileage is important to you, we would suggest the Hyundai Venue. We have yet to put the new generation car through our standard fuel efficiency test cycle. 

However, given that it carries over its powertrains, we expect it to perform better than the Mahindra XUV 3XO. The Mahindra car is tuned more for a peppy throttle response, and this drops its real-world fuel efficiency.