Had a 6cyl LX Torana back in the day...

Not really a repair but I got good at changing gears without using the clutch and timing my approach to traffic lights, when the clutch cable snapped. A couple of times

Had the cog in the ignition barrel partially strip at one stage, it was enough to turn the power on but wouldn't engage the starter...
I was too lazy and tight to go buy a new ignition barrel, so I used to do the old trick of shorting out the starter with a spanner to get her started.
I got sick of popping the bonnet everytime I went out, so I wrapped a piece of wire on one of the starter terminals and tied a string to the loose end. I then fed the string through the firewall to where I could reach it easily. I hooked up a spring to the wire I had put on the starter terminal, to keep the wire off the other terminal.

So to start my car I turned the power on with the ignition barrel, pulling the string engaged the wire to both terminals on the starter, car started, I let go of the string and the spring would disengage the wire and away I'd go.

My VW van drivers door mechanism broke for the second time. first under warranty. 2nd 4 years later. Price to fix it using genuine parts and labour $1200+ all because a 50c piece of plastic broke and then the pull cable broke. Fixed it with some rigging cable, Rapid fix glue (brilliant stuff) and a cable tie. less that $30 and about about an hour of work .

A mates kombi blew a spark plug clean out of the head, destroyed the thread and all.We mixed up a wad of quicksteel and bunged that around it, screwed it back in as best as we could.Lasted a few years before the engine totally died.

Exhaust pipe tied on using rugby sock

Problem with lower ball joints falling out easy fixed
(Sorry if any ladies are on this thread)

Most would think it is your right to repair modify you own car (within reg's/engineering std's of course) well the automakers are starting to try put an end to it..