As of now, the Vento is not offered with a sunroof. Moreover, to add the feature in the car, we would suggest you walk into the nearest service centres. You can click on the following link to see the details of the nearest service centres and selecting your city accordingly - Service centre.
Volkswagen provides the Vento with a 1.0-litre turbo-petrol engine that churns out 110PS and 175Nm. There is an option between a 6-speed manual and a 6-speed AT gearbox. Their claimed fuel efficiency figures are 17.69kmpl and 16.35kmpl respectively.
Every dealer provides different accessories with the car. Moreover, we would suggest you have a word with the nearest authorized dealer of Volkswagen in your city