Alot of cars get stuck in rains mainly due to the following reasons.
1) bad condition of car
2) water in the electrics
3) driver stupidity
4) poor visibility (forward & backwards)
5) cant see what's under the water
Diesels do better since there is less of a chance that water gets in the engine, whereas petrol cars can break down due to water getting on the plugs.
Best thing to do in PK is to avoid travelling as much as possible whenit is raining & NOT to be too adventurous with your vehicle in the rain. Just now i took my kid to McD's and i found a surf stuck int the mud less than 1 meter from the tarmac in F-9.
Drive safe guys.