UPDATE: More Car Details
Cole Wyeth
"Great list, you should consider adding some stuff about car keyfobs, through the study of keyfobs you can tell what make and year someones car is, and maybe even narrow down a specific model based on other factors, an example is when i deduced that someone drove a Ford made prior to 2009, because of the distinctive shape of the key and bow.
Some other car stuff i can share:
Drivers side door handle, if there are scratches on the back of it or on the bodywork behind it, it's a sign of possible marriage as it could be witness marks from a wedding ring
If there's a baby seat in the back that's a surefire sign of both marriage and a child
If there's pinholes in the rear seat (if it's a leather seat) it's a sign of a dog owner
If the rear seat is covered, that's also a sign of a dog owner trying to protect the rear seat from a dog
Chew marks are another sign of a dog, they often appear on things like locking tabs and baby seat anchor covers
Someone getting into a newer Rolls Royce, if they close the door by hand they are either not the owner or not familar with the vehicle (possibly a new owner), the doors on RR's have an auto close button
Alternating field-like pattern in the carpet is a sign of a recent detail or valet
On pre-2009 jaguars you can get an idea of the driver or passengers fingernail lengths as the boot popper is the growler button, lots of scratches might be long finger nails
If there's a haynes or other service manual on display, often means the owner does their own work, if it's an older or lower end vehicle it also could mean the owner has fallen on hard times
Mismatched parts are an obvious sign of an accident, some are dead easy like mismatched doors and panels, but others are harder to spot, especially by casual observation, and professional accident repairs are basically impossible to spot"