How long to stop stopping

Hello everyone.

I tell you:

I have a Chevrolet Spark Lt 1.0 from 2009 with 190,000 km. We acquired it about 2 years ago and we have never demanded so much. The maximum time we have walked in him without stopping 2:30 hrs. Now, we want to make a trip to southern Chile (from Santiago to Valdivia) and I have doubt about how much is the optimal time to walk without determining, and avoid any panne or whatever.

It is necessary to mention that he never demanded the car on the road; I travel to 90 km/h, and to advance I go up at 95-100 km/hy nothing more, that not to pass the 3x1000 rpm; I take the slopes knowing that it is a City Car, I never demand, if I have to go to 60 or 50, so it is.

I hope this doubt can clarify me.

Thanks for your time.