We recently ran out of fuel in Tata Harrier and what a bad experience it was.
Once the Tata Harrier runs out of fuel, it won't have a single drop of fuel for ignition as all of that is already consumed by it. Also if you would try ignition even after that, the battery would discharge and you would either have to call the Tata Road side assistance which charged us INR 865 or you would have to find yourself a mechanic who would bring a jumper battery. ETA of Tata Road side assistance for city is around 1 hour.
For TATA Harrier/ Safari, you would need two batteries instead of one for jumper as with one battery, ignition didn't work. The mechanic told us that two are required for big cars like TATA Harrier/ Safari. Thank god he had two and the car could switch on.
Also, when your TATA Harrier has completely run out of fuel, you would need minimum of 3-4 litres of fuel. With 1-2 litres it doesn't work and you would run out of battery even sooner trying for ignition.
Wishing you all the best for your journeys ahead and remember, never run out of fuel.