Just came back from an incredible trip with breathtaking views in Jujuy. From Purmamarca by Rt 52, over the Cuesta de Lipan, to Salinas Grandes, to Susques, then by Rt 40 (new or old one?) to San Antonio de las Cobres. Very worthwhile BUT you need a 4 wheel drive vehicle to go on the Rt 40 / 70. We got stuck in the sand, crossed dry creek and river beds, and hit many rocks a long the way. Saw only two 4 wheel drive trucks in the 130 +/- km drive which took 4 hours. Ended up under the bridge of the Train to the Clouds. San Antonio de las Cobres to Salta was another adventure. (Didn't return the way we came!) Rt 51 started off as dirt, then paved. But about half way to Salta the policia informed us the road gets closed at dusk. He let us go and told us to be careful. He wasn't kidding - falling rock zones, 1 lanes at times, mud, rocks, under construction. Not for the shy driver! But amazing views worth the effort to see! 4 wheel drive necessary!