Considering your running of around 1,000 to 1,200 km a month, it makes more sense to go for the petrol Mahindra 3XO.
In our real world economy test, the diesel was around 3 kpl more efficient than the petrol, which translates to a saving of roughly Rs 3,000 a month. However, the diesel is also over Rs 1 lakh more expensive, so it will take years to recover that extra upfront cost.
So, we’d recommend the petrol over the diesel. And if you’re looking at an automatic, it’s a no contest as the petrol gets a refined 6-speed torque converter, while the diesel comes with a relatively crude AMT.