It is very sad that you're having to retire your well-maintained Polo due to the 15-year rule in Delhi NCR. Since you have a budget of Rs 7 lakhs, we'd advise you to get a 2020-21 Maruti Brezza or Toyota Urban Cruiser, both of which are smooth, well-built cars. Their seating position is high, visibility is good, and controls are light, which makes them very user-friendly. 

Also, try finding the newest possible example, which will ensure that you drive the vehicle for 9 or 10 years before it reaches the 15-year age-limit.

For your outgoing car, you could consider getting in touch with used-car platforms such as Spinny; they'll do the paperwork, and should get you a good price.

Given your requirements, you should consider the Maruti Suzuki Brezza. The Brezza has a comfortable and spacious cabin that can easily accommodate four adults. It also comes with a refined 103hp, 1.5-litre petrol engine paired to a smooth 6-speed torque converter automatic gearbox. 

Maruti claims the Brezza automatic will do 19.8kpl. The Brezza is also relatively easy to drive, and being a Maruti product, it will also be stress-free to maintain. Maruti Brezza price for petrol-auto range starts from Rs 10.60 lakh to Rs 12.86 lakh (ex-showroom, India). 

The ideal car for your requirement is the Maruti Suzuki Brezza. Thanks to its wide rear seat, five adults can sit in good comfort, and the ride quality is comfortable enough even for long journeys. It is a proven product and, being a Maruti Suzuki, you can expect low maintenance costs and reliable ownership.

There are, however, two caveats. The Brezza facelift is expected very soon, so it may make sense to wait if you are not in a hurry. Also, the current generation of the Brezza has not been crash tested yet, while the previous generation was tested by Global NCAP and had scored a four star rating.

If you want to buy a car immediately, the Mahindra 3XO is another strong option. It comes with a more powerful turbo petrol engine that delivers effortless performance even with a full load. Its wider body makes it one of the best five seater options in the segment. It has also scored a full five star rating in the Bharat NCAP crash tests.

Within your budget, you can opt for the REVX A variant of the 3XO or the ZXi variant of the Brezza.

The ex-showroom price of the Mahindra Bolero Neo N11 is Rs 10 lakh, so you will have to account for costs of insurance, registration and other charges. That said, the Bolero Neo is a rugged SUV, with a surprisingly refined 1.5L diesel engine. Also, it has the ability to seat seven, which gives it an edge over the 5-seater monocoque compact SUVs available at a similar price. 

However, if you don't need that extra pair of jump seats, we'd recommend you to consider the Maruti Brezza or Mahindra XUV 3XO instead, which are a lot easier and more car-like to drive, and their driving dynamics are also much better than the Bolero Neo. These compact SUVs feel surprisingly robust, however if your usage majorly includes bad and broken roads, the Bolero Neo could be the better pick, simply for its toughness and abuse-friendliness.