What essential spares do you keep 'in stock'?

[fozzymandeus]

Essential spares I keep about me:

1. Spare complete car in full working order.
2. Err... there is no 2.

[harry_p]

in the car, in addition to the standard tools etc,,

puncture repair foam stuff, spare alternator and power steering belts, couple of bulbs, decent length wheel brace and a litre of oil. nearly always got my big tool box in the back too, but thats more because it's a safe and handy place to keep it than becaue i think i'll need it!

the only real 'spares' ive got for it are several sets of wheels (none with tyres!) and some of the standard bit's i've replaced (steering wheel, rear wing, front seats)

[Fushion_Julz]

I've got spare set of spark plugs for each car, a few spare belts (alternator and power steering), exhaust clamps (mainly for the van) and rubbers, thermostats and a spare 325 rad. I also have spare top hoses and a couple of other random bits of hose and finally a few spare wheel bolts and nuts.
I Have a few more spares for the M3, but they aren't exactly "essentials" and similarly for my van (Merc 609D)...Mostly they are parts that have been replaced but the old ones still have life left and are useful as spares...