Brand new BMW M140i. Great when it worked. Total sack of sh!t on balance  

Other cars have been pretty reliable. 
1989 1.3 escort pop - bullet proof despite reaching an oil consumption of 1pint/hundred miles- smoked like Del Boys van! 

1997 1.4 Astra hatch - needed fettling at the side of the road when I drove it through 2'  of water.  Also snapped a clutch cable, but nothing else from 76k - 113k when I scrapped it due to encroaching tin worm. 
2002 2.0D rover 45 - split IC hose and a failed battery between 40(ish)k and 90k. 
2001 Saab 9-5 aero wheel bearing replaced in 50k of use 
2001 Mondeo TDDI bought with a knackered dmf- otherwise no problems between 80 & 130k
2004 x-type 2.5 v6 - failed lambda sensor and a/c compressor leak (which I never fixed before selling) ran it for around 50k
2001 Saab 9-5 aero - ignition cassette (and a real thirst for oil). Otherwise a cheap year of motoring despite taking it from 160-190k 
2003 omega - passenger side door lock, ignition key jamming issue, busted glove box catch, temp sensor, otherwise only service items (I think). 
On balance, having never spent >£2,200 on a car until the Bimmer, I'd conclude I've got off pretty lightly. Either smart buying, or more likely- good luck.