Voice guidance for car navigation typically considers drivers as docile actors. Recent works highlight limitations to this assumption which make drivers rely less on given directions. To explore how drivers can make better navigation decisions, we conducted a pilot Wizard-of-Oz study that gives turn suggestions in conversations between two voice agents. We asked 30 participants to drive in a simulation environment using voice guidance that gives three types of suggestions: familiar, optimal, and new routes. We examined their route choices, perceived workload and utterances while driving. We found that while most drivers followed directions appropriate for the given scenarios, they were more likely to make inappropriate choices after hearing alternatives in conversations. On the other hand, two-party conversations allowed drivers to better reflect on their choices after trips. We conclude by discussing preliminary design implications for car navigation voice guidance specifically and recommender systems in general.