To easily reach Lentas or to start individual excursions, you do not need necessarily hire a car. One can travel relativily cheap with a taxi on the island. Especially a transfer between the airport / port and Lentas is recommended. A taxi ride from Heraklion to Lentas for example, costs 85 Euros (as of 2015).
In Lentas there are local taxi drivers, where you can directly book a taxi and they pick you up at the airport / harbor. On request, the Lentas taxi drivers try to find passengers traveling at similar times and have the same goal, taxi costs can be shared.
You can also organize a carpool, a forum for taxi-sharing can be found here: www.lentas-taxi.de
Also trips to the surrounding area or transfers to hiking trails, can easily be arranged with a taxi.