Remove interfering smells. Put the air freshener in the glove compartment. Test-driving includes test-sniffing, so do don’t let any smells disturb you. Sniff the air while driving, sniff the seats and the interior. You are going to breath with this. Put down the information about suspicious smells and inform your mechanic.
Adjust the drivers’ seat. Do you feel comfortable? Make sure you have enough room for legs, arms and head.
Adjust the steering wheel, make sure it tilts and telescopes and the position is comfortable.
Check redundant audio and cruise control buttons, make sure other buttons are easy to reach and working.
Adjust the mirrors, make sure the visibility is good.