Drove around for 9 months with a rachet strap holding the fuel tank in place on my Renault Espace.

Even passed an MOT with it on.

Ditto rachet strap holding a broken gearbox mount together on a Seat Ibiza.

Couple of rally car bodges but probably doesn't count as I needed to get the car out of a stage and back to service:

Leaking rear calipers clamped off

Broken track rod 'repaired' with two spanners and two worm drive clips

Probably many others...

Arwyn