Driving times for Peru?

Hello,

How accurate are the Google maps times for Peru? Specifically, I'm wondering how long it would take to get from Ollantaytambo to Andahuaylillas? It's listed as 100km, but taking 2.5 hrs. But I've heard that road around the sacred valley is good, and the drive is fairly easy by Peru standards. Am I really going to average 40 km/h?

Note: I'm a fairly experienced international driver. Driven a lot in Colombia, Mexico, and Costa Rica. But not in Peru (yet).