The test drive is always a fun experience for me. A chance to punch the gas and see how well the car handles. A commonly used sales tool in the industry is the "All-Day" test drive. It works quite well actually. You take it home or to work and you get that new car feeling where everyone says "OOOOOHHH. You got a new car!!". The euphoric sensation of self-worth. Thus giving you the thoughts that you just have to buy it now.
I suggest that you use this so-called "sales" tool to your advantage though. Let your friends sit in the driver's seat and press all of the buttons. Show it to everyone you know and let them pick out the problems/benefits of the vehicle. Remember, you are blinded by the "new car feeling". Your friends may notice that the interior panel on the passenger side back door is loose, or that there is some kind of black mark on the kick panel, or "What's that sound?".
So remember, remember the old adage: "Two heads are better than one". And turn that "sales" tool into a "buying" tool.