Recommendation: Just tell them you want to test drive the truck. Don't give them any other additional information to the effect that you have any particular interest in this brand or model. In effect you told them you couldn't live without this truck so the salesman, as is their job, was reminding you that you really should purchase it. It is the salesman's job to "hound" you as we say here. Call it what you will but a salesman's job rests in the power of persuasion.