Sure, I'll bite...

I carry:

The toolbox I got in 1972 to maintain my Datsun 1200.
It contains:
Metric combo wrenches from 7 mm to 19 mm
6 in 1 screwdriver
6 oz. engineer's (ball-peen) hammer
4" long nose & 8" standard Vise-grips�
wire cutter/crimper
6 fuses (2 ea, red, blue, white)
3/8 sockets (10 mm, 13 mm, 14 mm, 15 mm, 17 mm & 19 mm. Spark plug  
socket 3" & 10" extensions
1/4 sockets and ratchet 5 mm -13 mm deep
metric Allen wrench set
6 mm XZN socket
half a dozen M8 x 1.0 x 35 mm bolts with flat and wavy washers and  
nuts, ditto in M6.
Left over parts.
Digital multimeter
Datsun wheel chocks
1 bottle of oil
1 gallon of coolant
1 alternator/water pump belt (used)
2 Bilstein jacks
stock lug wrench

With the exception of the VW specifics (XZN & jacks), I've used the  
same set of tools for nearly forty years.

I can usually perform maintenance/ minor repairs on anything  
automotive without having to open the shop up.

Note that I do NOT carry spare alternators, starters, piston sets,  
cylinder heads, transmissions, CV joints, axle shafts, ECUs, AFMs,  
distributors, spark plugs, ignition parts, fuel pumps, radiators,  
window winding handles, crankshafts, connecting rods, ball joints, tie- 
rod ends, instrument clusters, ignition switches, brake drums, or the  
like.  If I need any of those, the list vendors are but a call away  
and Fed Ex can get it to me the day after tomorrow. It's not like I'm  
in Timbuktu.... If I need a part or a tool that I don't have, it's not  
a big thing.

Last but not least, I carry a 15' nylon tow strap.

Jim