As EVs are still relatively new, their performance after 15 years is still an unknown quantity. EV batteries are expected to have a shelf life of 10-12 years. During the course of which the battery's capacity to hold a charge will gradually deplete. 

After this point, it will have to be replaced, which is a high cost, although the savings on fuel over the years are expected to offset it. This, of course, reduces their resale value considerably compared to petrol or diesel cars. 

Public charging infrastructure is improving at a rapid rate, so the problem of busy chargers should be less with each passing year. But the best charging solution remains to have a charger at your home and at your destination, and to charge in small amounts as needed.

As for hybrids, the same battery concerns apply to them too - it's just that the batteries are smaller and therefore cheaper to replace. Self-charging strong hybrids aren't burdened with charging and therefore not dependent on charging infrastructure. But while they are super efficient, they still use petrol, which is expensive. Still, if you do plan to keep the car for 15 years plus, a hybrid would be a safer bet overall. 

Considering that you may occasionally need more than five seats and plan to keep the car for at least four to five years, we would recommend opting for a six or seven-seater. Because of this, the Hyundai Creta EV and the Tata Harrier EV can be ruled out, as both are strictly five-seaters.

The Mahindra XEV 9S is very competitively priced and comes loaded with features. The downside is the ride quality, especially in the second and third rows. It can feel a bit too soft due to the suspension setup. This is not much of an issue in city driving, but at highway speeds on uneven surfaces, the car tends to bounce as the suspension takes time to settle.

Since you had also shortlisted the Hyundai Creta EV, we would suggest taking a look at the Kia Carens Clavis EV, as it uses the same powertrain and battery. It works better as a six or seven-seater, thanks to a more spacious third row compared to the 9S, where even adults can travel in reasonable comfort. While it is not as powerful as the Mahindra XEV 9S. It still offers more than enough performance even with a full load, and the suspension feels more comfortable overall.

One important thing to note is the battery size. The Clavis EV has a smaller battery pack compared to the XEV 9S. In real-world usage, the Mahindra can deliver over 450 km on a full charge. While the Clavis EV is likely to offer closer to 350 km of realistic range.

Of the two, the Mahindra XUV 7XO is the better pick. The XUV 7XO is packed with tech and is far nicer to drive than the MG Hector, too. Mahindra's engines and gearboxes are highlights, and the 7XO's updated suspension also gives it the edge in ride comfort. Importantly, the 7XO offers a better third-row experience than the Hector Plus. 

That said, the XUV 7XO is not the best 7-seater for the money. Especially in case the third row space and comfort are a deal breaker for you. The Tata Safari offers a more comfortable third row among petrol/diesel SUVs of the segment. 

If you are open to electric, the Mahindra XEV 9S is worth a look. While you could think of it as an all-electric version of the XUV 7XO, the 9S does boast of a better third row. The option to slide its middle row seats makes all the difference to balance second and third row space in the cabin.  

Between the diesel Mahindra XUV 7XO and the electric XEV 9S, we think you would be better off with the XUV 7XO since your main purpose of the new car is to go on family trips. 

Highway charging infrastructure is still developing, and quite a few times, existing chargers are either occupied or not operational. 

Thus, if your trips are over 300 km long, you would need to stop and charge. This will ensure you can make it back or even have sufficient charge to drive around when you get to your destination.

Moreover, if these trips involve hill climbs, you will lose battery charge much faster. Conversely, the diesel Mahindra XUV7XO will be just right for these conditions. The torquey engine is powerful enough to tackle climbs, and with diesel being the fuel of choice, there will be no range anxiety.