The Tata Altroz diesel is a well-rounded car. It is spacious, feature-rich, good to drive, and the diesel engine delivers good performance while being very fuel-efficient too. Since your monthly usage is on the higher side, you will benefit from lower running costs by opting for a diesel, compared to a petrol/turbo-petrol car. Also, the Altroz feels reassuringly stable on the highway, and even passengers will be comfortable over a long journey.
With the Mahindra XUV 3XO, you get high seating and ground clearance, and its turbo-petrol engine is strong and refined too; however, efficiency will not be as good as the diesel Altroz. Between the two, we’d recommend you go ahead with the Tata car.