For the choice of variants in Audi A3, you may differentiate on the basis of fuel type. Follow the below link to get the details of the variants - Variats. Moreover, you can also follow the link to the article of Petrol vs Diesel - Article.
For this, we would suggest you walk into the nearest authorized service centre as they will be the better people to assist you. You can click on the following link to see the details of the nearest service centre and selecting your city accordingly - Service centre