Since your running isn't high - only around 6,000km a year - it would make sense for you to opt for the petrol.
The higher purchase price of the diesel won't be justified given your usage. For reference, the Mahindra XUV 3XO AX7L for the petrol-manual variant costs Rs 12.75 lakh and Rs 13.43 lakh for the diesel-manual (ex-showroom), and the price delta will only be greater when it comes to on-road prices.
