@smqtesting Just my view based on my own experience.
BRV and WagonR are two different classes and IMO are not comparable. I believe it would not be a bad idea to give your car about 20-30 minutes break after some 3 - 3 1/2 hours. I learnt from a technical man that with engine on, pouring water on the radiator really helps. After pouring sufficient amount of water, engine can be shut off to give it a break.
I was driving a Nissan AD (1300 cc) in my trip this June. And long stretch of driving with extremely hot sun out there can be too much for a car and its cooling system. Having said that, if you are driving at around 90-100 Km/h it might not put extra pressure on cooling system but if you try to be consistently at 110-120 km/h it might. Just my opinion.
Anyways, good luck for your trip. May Allah help you and make your journey safe, comfortable and enjoyable!