This one was mine, a 1998 Mercedes W208. The nice things about it were the cool Mono-Wiper, the engine (supercharged 2,3L M111) and the seats that were perfect for my height. It had a terrible ASR system but came with a LSD, so it was lots of fun in the winter.
The not-so-nice things about it were that the ignition randomly would not recognize the key, a missing catalytic converter, two fist sized rust holes in the front control arms, rust all over the underbody and the absolute worst 6-speed manual transmission I have ever used.
It also had multiple alignments but it didn't take long for the steering-wheel to be off-center again. You could see the tail end "crabbing" in the rear view mirror. There was something very wrong with it, which can probably be attributed to one of the 7 previous owners.
This isn't even counting all minor annoyances like the frameless windows not lowering themselves when you open the doors (that was only a thing after the 1999 model year), the wind noise, the awful interior materials, the broken seat latch in the rear, the trunk lock not working... I could go on for an hour like this.
So anyways, what is the worst car YOU have ever owned?
Mine was both the most fun car as well as the worst car I owned.
It was a Nissan 200SX S14. It was around 320bhp SR20 with uprated turbo, external waste gate, screamer pipe that vented upwards out of the bonnet and would occasionally spit flames through, solid engine mounts, welded diff, stripped interior among other similar supporting mods.
It was well built and was an absolutely visceral driving experience, it was insanely fun and also scary at times to drive and I fucking loved it when it was working.
However the Nissan immobiliser would just randomly decide when it would and wouldn't kick in. Sometimes it would start no problems at all and other times it took me and hour or more of cycling the ignition on and off. I got stranded places a few times where it would just refuse to start then I would have to return the next day and it would start first try no problems. It just had those electronic gremlins that I just couldn't figure out the actual issue and it was insanely infuriating.
It was the epitome of a love hate relationship and without those starting problems would have been one of my favourite cars but I just never figured it out and ended up selling it on never having solved the issues. Was such a shame.
Whoever reprogrammed the engine management probably fucked the security system.
The Nissan NATS system could be an absolute bastard, yeh xD
It's a pity we often cannot maintain our machines, not because we don't want to, the OEM have made them impossible to modify or repair. Anything with software in it is becoming an absolute nightmare.
I mainly worked on 90s Japanese cars, I primarily had MX5s and 200SXs which were mostly alright to work with as they did have minimal electronics. However still getting into the world of management and ECUs was always more complex.
I've been out of the world of cars for more than 10 years now as I simply can't afford to run a car and also afford rent / to eat these days which I have come to terms with but I would never want to work on these horrible modern cars where everything has so many sensors and electronic dependencies.