I had some utter crap boxes as a student, but they were cheap and my expectations were few.
My worst car, measured by unreliability and repair costs was an almost new Mk I 225 TT coupe. Over the five years I owned it, it left me stranded three times and the total warranty claims exceeded the purchase price of the vehicle.
The failings ranged from the ridiculous (the clutch pedal mechanism failed, leaving the pedal on the floor with the clutch engaged), to unusual (the gear selector fork for third gear snapped leaving it stuck in third gear) to the completely unacceptable (the timing belt failed wrecking the engine 20k miles and several years before the schedule belt change).
Dynamically, it was rubbish with handing typical for FWD-biased 4WD cars, failing into understeer at the limit of grip. There was little feedback from the steering and the brakes were hopeless, overheating with any enthusiastic driving. It always had a least one warning light and accompanying chimes (side light bulbs several times each year, washer fluid, false brake pad wear warnings) and the warnings meant that a large part of the display was replaced with an annoying yellow, pixelated graphic
The positives were that it was fast in a straight line and very happy to cruise at over 100mph for hours at a time, and the interior was a rather nice place to be when waiting for the recovery truck to arrive.