Harsh driving conditions are your A/C is continuously on and weather is hot like 40 c and you are stuck in a traffic jam of Lahore , Karachi , rawalpindi and 5 kilometer distance is travelled in 4 hours that's harsh driving condition.................
2nd scenario is
You are on a hilly area and you had floored the pedal like you are racing on your vitz with a prado on hill climb conditions with A/C full on with 5 persons on board.
3rd scenario is you are on motorway and every after 2 minutes you touch your top speed along with A/C and 5 people's on board.
Hope you understand the harsh condition word used in automobile's.
Any further information required??that's best I can explain else seniors will band my head on a Mustang 69 hood