What to record in writing, not just in photographs

Photographs do not capture everything. Write down:

• Odometer reading: the number, not just the photo.
• Fuel level: as a fraction or in eighths. "Full" and "three quarters" are the two that cause arguments, so be specific.
• Existing damage, described in words. "Scratch on rear-right door, about 10cm, already present." A photograph shows it; the note proves you both saw it.
• What is in the vehicle: spare tyre, jack, early warning device, tools, child seat.
• Date, time, and who did the inspection.
• The customer's acknowledgement. A signature, or at minimum a note that they were present.