What are some good emergency trunk tool "must haves?" Like some common metric size tools, or just a good ol crescent wrench?.. Pliers?... What do you have stashed in your trunk for that emergency situation? Besides a cell phone and a AAA membership... Granted I don't want to lug around my whole toolbox.

I, for one don't leave the garage without a 3M scuff pad in the glove box. That stuff has gotten me out of many an electrical problem, and no-starts.. Anyone else?

I think if you remove the spare tire, you can wedge a Smart Car in the trunk to drive for help or get spare gas if you run out in your Brick.......

simple non-digital multimeter
full set of combination wrenches...8, 10, 12, 13, 14, 15, 16, 17
1/4 ratchet, sockets to 14mm, two extensions
test lamp
folding 4-way
duct tape
bailing wire
flashlight
150 grit sandpaper
cool 14-bit screwdriver
long flathead
LARGE channel locks
RTV
half a mountain bike inner tube

That's a pretty complete list.
The only thing that I might add is my (homemade) 12' long, 16 gage jumper wire with alligator clips. With it, you can put 12V power anywhere on the car for troubleshooting.

steve

Half a mountain bike inner tube?... Whats that for?

Also, since actual bailing wire is getting hard to find, rebar tie wire at your local big-box store works just as well.

I did not include it in the list because it is always in my glove box and/or armrest console but a Leatherman-type multi-tool with the wire cutters and needle-nose pliers is essential. This, the channel locks and the 1/4" socket set are places I do not cheap out (and flare wrenches but I do not consider them emergency tools).

All kinds of things:

Combined with Duct tape a section can be used as a temporary heater/radiator hose patch

Since it is stretchy it can be used anywhere a rubber band can...only bigger

If you have two things touching that should not be touching, stick a chunk of inner tube between them

Those are only the ones that come to mind that I remember using it for.

I used to carry 19" front wheel motorcycle tube on all my motorcycles because in a pinch it could serve front or rear (rears tended to 17") but then I found that more often than not I ended up cutting it up to do things like to tie a saddle bag shut or put between the seat base and the battery post when metal seat pan kept contacting the post.