Good idea. My car is pretty rattly now and it's one of the younger ones.
Things I have fixed or at least understand
- loud rattle from footwell when going over broken surfaces, not over big bumps:- drop links
- loud ker-clonk when going over speed bumps:- anti-roll bar bushes
- chirp from under back seats when engine coldish:- could be exhaust silencer going, long thread on here somewhere
- groan or clonk from tailgate when going over speed bumps:- tailgate moving too much, adjust the rubber bump stops on either side of the tailgate. Not too much, or the tailgate will be hard to close
- squeak from around gearstick:- could be the plastic gearstick surround rubbing on the main centre console, (under ash tray). Wedge something between the two e.g. a credit card
- rattle from back seat backs, only when they're upright :- lube back seat catch. The catch has two parts, an inner metal rod and an outer plastic sheath which should spring into place and stop metal-on-metal between the rod and the body attachment. The sheath can get stuck hence the rattle. So lube your rod and sheath (fnarrr)
- door card rattles:- loads of these
- the inner door handle is shonky, the two parts creak where they rub together. Drop some super glue where they meet, mask it off with tape maybe?
- where the door card meets the metal door frame can creak, particularly at its rear edge. Pad it with something soft so the card doesn't touch the door
- the plastic clips which hold the door card to the door can break, they rattle like &*&&. You can get the clips off eBay, easy to pull the door card and replace. You might find the mounting point on the door card is broken too, in which case do without that clip, you don't need them all
- where the top of the door card wraps round and meets the window can creak. Pull the door card, put a couple of layers of black tape along the ridge which it hangs from
- there's a plastic grommet thing between the rear window winder and the door card, the clips on it break. A dab of glue fixes it (manual rear windows only)
All these rattles are way worse on a cold morning.
Things I haven't fixed:-
intermittent buzz from the hood over the instruments. a good jiggle fixes it sometimes
intermittent buzz from the centre console vent slats, a good whack on the top of the console sometimes fixes it
a boing like a spring moving from either the handbrake or the passenger seatbelt catch
a buzz from under the glove box when cold
a tick tick tick from near the driver wing mirror
a tap tap from my right ear, probably the seatbelt height adjuster
my new duh-duh-duh from the blower fan
etc