Price wise the BMW X1 makes sense as it is much cheaper at Rs. 31lakhs on road Mumbai while the Audi Q3 is priced at Rs. 42lakhs on road Mumbai as it attracts more taxes being a CBU. The Audi Q3 is a 4WD while the X1 is a 2WD. Take your pick.
Audi doesn't offer it as an optional feature, however you can try to get it by authorized Audi dealership, there are also a few aftermarket options available. Cost of the job will be around Rs. 20,000.
Audi doesn't provide these details for the Q3, however the legroom and headroom in the SUV are adequate only. The legroom and headroom are fine at front seats, but at rear bench the tall passengers (around 6ft and more) will face problems due to limited legroom and at the same time the sloping roofline makes the headroom another issue.
You can see the legroom and headroom at front and rear in below given images
In the picture you can see that when the front seat has been pushed behind maximum, the legroom at rear will be quite lesser and the sloaping roofline almost touches the headrest.